We heat over 2800 sq ft with a little Harmon pellet stove. We set the temp for 68 when we are here. It drops down to 64 when we are at work. My dh is a heating tech. and says that it really doesn't make sense to lower it too much when you are away, because it puts a strain on the equipment to bring the house back up to temp if the difference is really large.
We burn about one bag of pellets (40 lbs) per day when the outside temp is above 20 degrees. We burn about a bag and a half on the chillier nights when the temps are near 0 or below.
I like the pellet stove because it provides a place to really get toasty if you need to, while keeping the rest of the house comfortable.