There is a very nice RV park called Distant Drums in Camp Verde between Flagstaff and Phoenix. We stayed there last year for 5 nights and explored Sedona, Jerome, Cottonwood area. Really nice to stay outside of the now very touristy Sedona. But it is very beautiful to drive in to see and not very far from Camp Verde. Also we loved Tuzigot and Montezuma's Castle. Both close to Camp Verde.
Depending on the kind of rig you have Flagstaff KOA can be a tight fit and we don't recommend for larger RVS. We are 40 ft with 3 slides and the site and roads inside park were not easy to navigate. Doable, but I'd book elsewhere if you are larger rig. We also spent an evening at the Lowell Observatory and had a great time.
Kreig and Robin
2008 National Pacifica 40E
Towing 2014 Jeep Wrangler