Good link for checking regulations for pets at National Parks.
http://www.petfriendlytravel.com/?page=national_parks
Most seem to allow them in campgrounds, but there are other restrictions.
I have been looking at Wyoming campgrounds myself. I will be in Custer, SD until June 8th, and I haven't decided how or when I will make my way back to Little Rock. I am looking at driving I-80 west and then dropping down through western Colorado and then into New Mexico.
Anybody know what I-80 from Cheyenne westward is like as far has how mountainous, curvy, etc?