SW Utah: Grafton, near Zion NP--some restoration and stabilization three years ago to the buildings.
Rhyolite is OK, but Gold Point and Goldfield a couple of hours north on US 95 are better. Both are about 4-5 hours north of Las Vegas.
Haven't been to Paria (movie set town) in 20 years so I can't comment, but some of the other little towns in central Utah are very interesting photographically. Be sure to ask permission if you think you may be trespassing.
A few years back north of Bryce, I did go to Osiris, though it wasn't much to shoot.
Cisco is getting to to more of a wide spot in the road. Less to photograph there each time I go. 2003-2004 was enough for a few photos, not much more.
Sunset Publishing used to have "Ghost Towns of the West" published in the 1970s. I went to many then and into the 1980s. Much is now gone and new ones are developing, especially in the western Great Plains as people move out of the Rural West.
There are lots of places you can find on such sites as
http://www.ghosttowngallery.com/ which seems to have a pretty good link page.
For Wyoming, I like shooting in Atlantic City and South Pass (a state park). Still lots of good buildings at each.
The two best by far, and best preserved are Bodie in California, about two hours south of Reno and Bannack, Montana, a hour west of Dillon in s.w. Montana. You can spend a day or more in each and still have enough to bring you back.
All of these are easily accessible without 4WD.
Also, do a search on Amazon for ghost town books. It seems that each state has some kind of guide book that will give you great ideas.
Have a blast shooting, and leave some pix for the next guy!