As a kid, I spent many summers in Kanab, Utah visiting my Grandmother. It is centrally located to so many National Parks and beautiful sights, Zion in 45 minutes away, the North Rim of the Grand Canyon and Bryce about 80 miles away in opposite directions.
I've never stayed at any RV Parks there, but I found this link for you:
http://www.kanabrvcorral.com/
Here's more info on Kanab itself:
http://kanab.utah.gov/ and
http://www.visitkanab.info/
Have a great trip!
Kelly