What should my weight loss goal be?

I wouldn't change a thing unless you're getting stuck in a rut. I'm sure there are some experts out there who will have more input, but if it ain't broke don't fix it.

You are 100% correct. As you approach your ideal weight, your weight loss should slow down. Your body might already consider itself "healthy" even if you still want to lose a few more pounds. Those last few pounds are sometimes referred to as "vanity pounds" because they are no longer a health issue, you just want to look good. (Not that there is anything wrong with that) You can't lose vanity pounds with huge calorie deficits. Your body will kick into platuea mode much sooner. If you take it nice and easy and plan on no more than a pound a week, you should be fine. Jillian Micheals talks about this on her podcast all the time.

One other thing of note... when someone who has a lot to lose is first starting out I would suggest more cardio and less weight training (while still doing a mix of both). The closer you get to your weight/size goal the more I would I change the ratio to favor weights over cardio.

Just my 2 cents.

I have about 20 lb. left to lose after having lost 47 lb. I've heard people say they have more success pushing the last bit of weight loss by changing their weight loss goal from 1 lb/week or 1/2 lb/week.

What are your thoughts on this?

*If it makes any difference, I do circuit training 5x/week for 30 minutes.