My recommendation is a cyclocross bike. But it depends on what you think you'll be riding on most. Mud, ice, or sand is going to cause pretty much everything to suck except a fat tire bike, and that will suck anywhere *except* mud, ice, or sand. A 'cross bike is great for tarmac, gravel, greenways, and lighter singletrack. My 'cross bike is my "jack-of-all-trades" bike, and by far the most frequently ridden besides my road bike.

Haven't came across touring bikes with that tire width but lots of cyclocross bikes. Keep in mind most CX don't have attachments for bicycle panniers (it get really uncomfortable carrying everything on your back). I ride with 28 mm tires on my race bike and it's does just fine on short stretches of gravel, sand, and cobbles. (See Paris-Roubaix if you want some confirmation). Just yesterday I rode through half a mile of gravel road while exploring a new route. Good luck with aero clip-on especially lugging a load. They take time to master and don't get dishearten if you find no one wants to ride next to your while tucked. My personal rule is to stay away as far as possible as I enjoy staying upright on the bike.

I had the same goal this past year. I wanted a bike that could take me all the way backcountry on multi-day trips far away from the recreational riders and casual campers. I considered a Salsa Fargo and a Surly ECR.

The Fargo has a cult-like following for bikepacking. It is a 29er with drop bars, 2.3 inch tires, a traditional MTB drivetrain, and last year it came with a carbon fork. The Fargo seemed to be ideal for rail-to-trail pathways, rough gravel roads, and moderate single track. This year, the Salsa Fargo 2 is supplied with a steel frame and available with a suspension fork. See it here: http://salsacycles.com/bikes/fargo

The Surly ECR is dubbed a 29+ as it deviates from the Fat Bike genre because it has 29er rims mounting 31-inch tall, three-inch wide tires. It looks like a Fat Bike but has taller and narrower wheels and tires. Because of the wheel and tire specs, this bike is much, much faster than a standard Fat bike with 26-inch tall, 3.8-inch wide tires. The Surly ECR is designed for long-distance, off-road touring and it really excels in this niche. It's a heavy duty design weighing 33 pounds or so and incorporating an upright touring posture. The Surly ECR is supplied with a steel frame incorporating an ED-coating for rust prevention. See it here: http://surlybikes.com/bikes/ecr

I ended up ordering a Surly ECR as the Fat Bike thing really intrigued me. I'm glad I bought the ECR in the end. I ride my Trek Superfly MTB with a triple ring Deore Drivetrain in rolling hilly terrain so I wondered if the 1 X 9 drivetrain of a typical Fat Bike would have worked for me. The 2 X 9 drivetrain of the Surly ECR works quite well in hilly, twisty single track, and I can roll over anything with those big tires. At the same time, low speed handling is really stable and awesomely responsive. I can track stand forever on this bike, especially so with a heavy multi-day load onboard. I have customized my bike with Surly front and rear racks among many other modifications to taste. The only component changes I must mention here is most Surly off-road touring / bikepacking bikes are supplied with Microshift SL-T10 shifters and low-end grips. The Microshift shifters are long-throw with a really vague feel so I kept missing my desired shift changes. I ended up swapping out the Microshifts with Shimano Deore XT shifters and that made all the difference in the world. While I was at it, I also swapped out the cheap, hard Velo grips for Ergon grips. The Jones Bar features a really comfy reverse sweep with a lot of hand positioning options, but you may experience a bit of Tunnel Carpal Syndrome pain using the bar ends with the standard Velo grips, as I did. So I chose to retrofit the ECR with Ergon GC1 grips and that cured the tunnel carpal syndrome problem. I also added a Serfas Tegu saddle (awesome for me!) and Shimano Saint MX-80 flat pedals. My Surly ECR is currently the only bike with flat pedals I have, and I wear my Five Ten Impact cycling shoes specifically to grip the wide rugged surface of the Shimano Saint MX-80 pedals. WOW! What an awesome combination for backcountry travel! I wear both the Impact Low shoes for the warm months and the Impact High shoes for the cooler months. If you want to receive photographs of my Surly ECR or if you have more questions to ask about the Surly ECR or the accessories I chose, feel free to private message me with your e-mail address and I'll reply to your request within a couple of days.

Salsa Fargo or a "monster cross" style bike. The Surly ECR as mentioned above is also an amazing bike. Fat bikes are not novelties!

Just remember, always adding a bike is an option.

I have a Specialized full carbon road bike, a Trek mountain bike, a Trek touring bike, a 30 year old tandem, and a 20 year old REI hybrid. With fatter tires, the hybrid took me everywhere I wanted to go. I did light mountain biking with it. The hybrid was my bike for 15 years including a summer of cycling Scotland, Germany and Switzerland. Then, I got the new bikes int he rode they are listed.

If I had to do it over again, I would have started with the Trek 520 Touring. It is the classic touring bike, has been around forever. I picked mine up used over the internet. People who own them usually take care of them. It is a bit heavy, but handles well when I add the packs. It came with both front and rear packs. Just my two cents worth.