I can't do a fair comparison of very many marathon courses, as to date I have only run one full marathon. Buffalo was relatively flat compared to where I train. Some of the out and back and loops were mentally challenging because I wasn't familiar with the course; from mile 20 or 21 onward it constantly seemed like I should be about to turn a corner and head down what passes for a hill to the finish line; but that doesn't happen till mile 25.

Rochester NY had an extended distance on the Erie Canal Trail for many years, and runners complained that this was incredibly boring. That stretch to trail is okay for cycling, but I about died from boredom doing a 4 mile training run on it. In 2015, the course changed to a loop done twice plus a tail end. I ran the half, only going around the loop once. It starts on the top of the Niagara escarpment, runs down the Riverway Trail almost to the lake, and comes back up on the other side of the river. You get to see all 3 waterfalls within the city of Rochester. There is a short but steep hill at mile 11 of the half, which would be mile 24 of the full marathon. I liked the half course well enough that I signed up for the full in 2016. It helps that this one is local to me. Next September I'll get an idea of how running that loop twice affects my perception of the course. That another time down and back up the elevation change from the Niagara escarpment. Rochester is now a net uphill marathon; a local runner who ran 3:00 at Boston in 2015 ran Rochester 2015 in 3:11 and called the course "challenging."

And of course, Boston. A lot has been written about Boston. I've talked to several people who have run Boston, some of them several times. Their perceptions of the course, the downhills, and Heartbreak Hill are all over the map. Monday I'll form my own first hand impressions.

Niagara Falls International Marathon is on my bucket list, for the scenery and the net downhill. (That, and it's close enough that travel is very manageable.) I'm told it typically has a head wind off the lake that negates the impact of being net downhill, but I like the scenery there.

Chicago and New York are not currently on my bucket list, but Chicago may become an implied obligation if I happen to time qualify for it at Boston. I know next to nothing about New York and Chicago, other than the fact that a buddy of mine has them both on his bucket list.

I've only run 3 so I'll give a review of each. I don't think a large number travel for any of these with the exception of perhaps the Kansas City Marathon.

Kansas City Marathon is a hilly course, making it a challenging run but it was also very enjoyable. I ran it last year (2015) and felt it was very well organized. It had plenty of volunteers, aid stations were sufficient, and there were plenty of people on bikes going up and down the course to help those requiring assistance. The expo was one of the largest I've seen in this area for any event. It is currently the only full on my calendar for this year, so they at least won my repeat business. It is paired with the Des Moines Marathon held the next day as part of the I-35 marathon series for any Marathon Maniacs who would like to do a back to back marathon Saturday and Sunday. I have not tried this myself (maybe some day, but I'm nowhere near capable of that right now).

Gobbler Grind Marathon (Overland Park, KS) - This was a much smaller event than the Kansas City marathon but was still pretty big for being a smaller race. It starts and ends at a scenic office park named Corporate Woods, beginning with a short distance through the office park and then going off onto the streamway trails along Indian Creek out to Olathe, KS with a small diversion through some streets to get some elevation I guess because that was the most hilly portion of the course. It was well staffed with aid stations every couple miles, and had plenty of on-course support as well. There were not all that many volunteers cheering on if you are looking for that sort of atmosphere though. The entire course consisted of a mix of road, pave trail and even a short section of dirt trails (no water crossings). There wasn't really an expo, just a packet pickup at a local running store. I can't say anything negative about this race, but at the same time I'm not sure that it offers anything truly unique. It is a nice smaller race. I am signed up for the half marathon at this event this year.

Pilgrim Pacer Marathon (Lenexa, KS) - Obviously another fall Thanksgiving themed race held a week after the Gobbler Grind listed above. This is a gem of a smaller event, I think the numbers had to be in the hundreds, I would be surprised if it broke 1,000 people at the starting line. Despite being small it had a whole lot to offer, and I would say that "per runner" it offers the most bang for your buck of the 3 events I have run. It is manged by a local trail running group called "Trail Nerds" and the race director is Ben Holmes who also holds most of the better trail runs/ultras in the area. This course is in parks along paved streamway trails and it is the only paved surface event this group hosts each year. The trail runners volunteer for this event and use it to help raise awareness and funds for their group and to support/develop local trails. There is no expo for this really, just a packet pickup. At the starting/finish area there is plenty of food from pies brought in to many, many homemade goodies brought in by all of the volunteers ranging from chili to even homebrewed beer! The aid stations are the best stocked I have seen of any race and I think part of this is due to them being ultra runners. There are water/electrolyte drink only stations, but there are also stations with food, and I don't just mean gels, they have cookies, fruit, etc, even electrolyte tablets. Despite being small, it has all of the amenities you would expect from a larger race. The volunteers, all being trail runners, are very friendly and helpful. I don't think I can give this event enough praise to be honest. I am signed up for their half marathon event this year.

I would just like to mention my local marathon. The California International Marathon, which follows a somewhat downhill course from Folsom, where the famous prison is, at the start of the foothills to the Sierra Nevadas, down along the American River, to the California Capitol Building in Sacramento.
Because it has a net loss of elevation (300 feet), many use it to get a Boston qualifying time. (Just a small loss, in our opinion. So far, Boston agrees with us.)
The only problem with the race, in my mind, is that it is held in December. December can be iffy weather in California. This past year the temperature was in the 50s F, perhaps even a bit warmer by the end, and the sun shone beautifully. But there have been years where it has been around freezing at the 7AM start, and about four/five years ago there was just a drenching rain -- literally 1-inch deep water coursing along parts of the race streets.
Still, it is well run and large enough to be an exciting event but not so overwhelming like, say, Chicago.

@tufel I know so much about CIM! A team mate of mine ran there last year and a ton of female runners qualified for Olympic Trials marathon there. It sounds like a gorgeous race.

I have run eight marathons. Some are repeats of the same course. Some are the same location for the race with an altered course.

City of Oaks (Raleigh, NC), 2013, 2014. Not a flat course, but a very nice run. Same course both years. Much of the course is on Greenway paved paths (basically from Mile 10 to Mile 24). It is also basically an out and back race course. It starts and ends at the NCSU Bell tower. The first six miles run you through downtown Raleigh before taking you west and the north of the downtown area. You split off from the HM course to run on the greenways. The full marathon is much smaller than the half. There is also a 10K that starts behind the FM/HM that follows part of the course and ends back near the starting area. Once on the greenways, there are few places for people to come out and cheer. There is a killer hill at mile 22.5 and there is about 1100 feet of vertical over the entire course. Not a huge marathon and because of the greenway it has to be limited in size. You'll mostly be running alone.

Hilton Head, SC, 2014, 2015. I ran the inaugural race in 2014, and came back to run it in 2015. They changed the course somewhat between the two years. It is basically a flat course except for the four times you have to cross the bridges across Broad Creek. You spend a lot of time on the Cross-Island Expressway. The first two years it was run on the first weekend Saturday in February. Neither time I ran it was it particularly warm on race day. It was raining from Mile 3 to Mile 23 and 42°F in 2014 (though the next day it was perfectly beautiful weather and would have been a good race day). In 2015 it was sunny but cold at the start (32°F). It did warm up to the high 40's and low 50's by the end of the race. The have moved the race to the second weekend in February now that Myrtle Beach has moved their marathon to early March. It was well-organized because they had previous experience running a HM, 10K and 5K. The organizers dropped the 10K and added the FM. The marathon is the smallest of the three races (around 200 entrants, about 170 completing the race).

Myrtle Beach, SC, 2014. I ran this course the weekend after running Hilton Head (above). I obtained a comp entry and decided that I was trained reasonably well to run marathons on consecutive weekends. The course is nice and flat with only occasional gradual undulations along the course. Less than 400 feet of total vertical climbing over the entire course, if that much. As cold as Hilton Head seemed the weekend before, this was colder (25°F, with a windchill of 19°F before we even started running) and ended up with a 25 mph headwind after Mile 17. There are plenty of entrants so you are rarely completely alone on the course if you are a middle of the pack runner. Without the wind, it is flat and fast. Believe it or not, my current PR was run in that race cold, wind, and the marathon seven days earlier notwithstanding. The marathon has been moved to the first weekend in March in search of better weather conditions.

Rock 'n' Roll Raleigh, 2014, 2015, 2016. No matter what your feeling about their policies about packet pickup, their use of charities, their cost, or their limited corporate partners (e.g., Brooks. The other riff-raff are kept to less spacious areas in the expo) or whether they favor HM runner over FM, they are extremely well organized with plenty of volunteers to execute all aspects of a successful race. There were a few hiccups on the inaugural race in 2014. It was on Palm Sunday and with all the churches in downtown Raleigh the course had to be altered. The race was also sold out and there were significant parking problems that caused the race start to be delayed.

The three RnR Raleigh races have all been on different courses. They have shared the same first nine miles in the three races with a significant amount of climbing. The first race in 2014 also had three huge hills at mile 16, 19, and 25. It also got warm after being cold all spring. It took its toll. Last year the course was changed to "flatten" the course. Well, the hills are not as steep, but my GPS tracks from last year and this year reveal a greater overall vertical climb. There is still the one steep climb at mile 25. In discussion with a number of marathon maniacs that have run many more races than I, they shared their thought that this is one of the hilliest courses they have ever run. It's my backyard, so I can say I am more accustomed to it. The weather this year was colder than average but the weather can be pretty extreme in the first couple of weeks of April. Next years race weekend is April 1-2.

Training for my third full now although I've done this course as the half so will add it in my comparison:
Asbury Park Full - 8 loop course from hell. Very flat but 8 loops is just sick and wrong. Needless to say this one isn't run anymore but it was my first so will always hold a place in my heart.

NYC Marathon - 2015 finisher and OMG what an experience. Course is hard....harder than I expected and I expected hard. I think Brooklyn is uphill in both directions and the Queensboro bridge is not to be messed with. I CAN NOT WAIT to do it again. Will do the 9+1 in 2017 to guarantee 2018 entry.

Lake Placid Marathon - did the half and loved the course and the marathon course is the half with some more obviously so am really looking forward to it. Its beautiful and the volunteer support is amazing and its not as technical as you'd think given the location in the Adirondack Mountains.

Bucket list races....MCM for sure, Chicago, Shamrock, and the Wineglass Marathon. There are others but these are a few. Well Boston of course but that would have to come with a hefty price tag for the charity commitment because I won't qualify until I'm like 85 or something.