Between Camp Verde and Cottonwood is where we stayed when doing Sedona Area, this is a great boondocking area for big rig access and has a Thousand trails park there also hich I have heard take drive ins as well. There are a couple of good RV parks and a state park at Cottonwood. Also on I17 there are a couple parks that looked OK. There are a lot of things to see around the Sedona area and the Cottonwood area as well. Jerome(DO NOT TAKE YOUR RV HERE!) ruins all around Cottonwood and the road I17 Camp Verde to 179 to Sedona(and the things to be seen here are great). This is like 10-15 miles from Sedona and the intersection at I17 and 260 has fuel and such with EZ access.
I would go west a few miles to Williams and stay at the main RV park there run by "The Train" It is really nice. Just Google "The Train" for reservations. While you are at it, ride the train if you haven't already. They have a discount going right now.
Williams is a great little town.....old Route 66. And if you're staying in Williams, the Roadhouse is a great place for a steak! You order what ever kind of steak you want and they give it to you......the grills are on the customer side of the counter, along with all the spices, condiments, etc. You cook your own steak. Very clean and very nice atmosphere.....classic cars (he's always got 5 or 6 cars and trucks in there), etc. It's across the parking lot from the Harley Dealership.
There are a couple of boondocking campgrounds between Sedona and Flagstaf. Oak Creek Canyon would be ideal but not sure if there are any RV parks that I can recall.