Arizona is wonderful! However, I would not recommend making a base camp to tour in all directions of 150 miles. Instead, move from area to area and you'll enjoy it more. That's entirely too much driving time and fuel to travel that far daily. You wouldn't have any time to sitesee. Moving is not a big deal.
Secondly, elevations at 5,000' and lower starts getting hot in April. The higher elevation areas - above 5,000' - to zero in on from April on would be Flagstaff area and Payson, Show Low, Pinetop, Greer areas. Even Grand Canyon is hot from May on... The hot areas are certainly doable but not much fun. Plus, it's harder to keep the RV cool.
Arizona is all about elevation so choose your places based on it.
Full-Timed for 16 Years
.... Back in S&B Again
Traveled 8 yr in a 40' 2004 Newmar Dutch Star Motorhome
& 8 yr in a 33' Travel Supreme 5th Wheel