Widtsoe - couple old houses, a few residents still here. Best building is the old schoolhouse/chapel

Osiris - This is just up the road from Widtsoe. It's an old mill or brewery of some sort. They've posted no trespass signs, but you can probably get away walking around in it.

Gold Hill - Still some residents here, but cool old buildings at the main intersection. This area is more fun if you explore the old mine tailings and workings on an ATV.

Ophir - I think this little town has kind of been spruced up. Doesn't have much of an abandoned feeling anymore. That being said, their is a really nice old building way up the hill that I've seen that I haven't explored, it looks awesome. Plus the other side of the mountain is Jacob City which has a couple little things.

Amasa Valley - This isn't really a town, but it has some abandoned stuff and is a cool little valley above the West Desert.

I've probably been to a few more, but I can't remember. I do want to explore Frisco, and the mountains just to the west of Hamlin valley. I've been searching Google Earth, and there are a couple old mining areas all along the Pony Express trail that would make for a really fun weekend.