Spent a week exploring the Sedona area a couple of months ago{ last May} and a week just south of Flagstaff {Pine grove CG} in July. To explore Sedona we stayed at and thoroughly enjoyed Dead Horse Ranch State Park in Cottonwood. We had been in this area several times over the years and knew what to expect. Harold's hysteria aside... Sedona is still a lot of fun and drop dead gorgeous.
Yes, Sedona is crowded but that has had little effect on the views. We cruised the area on the back of my Harley which eliminated most of the driving issues. Hit town before 11 for the best experience. No the many, many round abouts are not problem except for a few folks who simply don't know how to drive but you find them pretty much everywhere.
As noted Do NOT drive Oak Creek Canyon in an RV especially if towing anything. Vehicles over 50' are outright prohibited and there is extensive road construction continuing at the north end of the canyon. December may bring snow, Flagstaff got 6 inches on may 9th and the temps in OCC were hovering in the mid thirties. The first 7 or 8 miles of OCC as you head north out of Sedona {the road}, is terrible with lots of potholes and virtually no shoulder.
Take a ride {in your toad or tv not the RV}, up to Jerome. I recommend Haunted Hamburger at the top of the town for a spectacular view {and great burgers}. The Tuxigoot Ruins and Verde Valley Railroad should be on every visitors short list of fun stuff as well.
I-40 from Williams into Flagstaff and I-17 from Verde Valley north to Flagstaff are two of the worst stretches of interstate in the country. Lots of severe potholes and poor concrete band aid patch jobs that are almost worse than the original pothole. Lake Mary road is a delightful alternative running south from Flagstaff all the way to 87 south of Happy Jack.
:C