The Cowboy Museum of the West (or something like that) in Oklahoma City is fantastic. We spend an entire day wandering about, would have liked to spend at least another day. That said, My wife and I are both western folk, my wife was a barrel racer in her childhood life. Then, I think in Clinton, just west of Oklahoma City and entire town is dedicated as a museum to Route 66. Old barns, equipment, stores, etc. Again we spent a day. In Amarillo we stayed at The Fort RV park. Lovely with a little lake. We didn't go to the canyons about an hours South, but it is in our to do list. The Petrified Forest is a fun half day tour. The National Park museum is at the South entrance, so from the 40 you really need to drive the whole tour to get to the information area. Again, we really enjoyed this. At the Grand Canyon we based in Williams at the Circle of Pines KOA. Really a resort lovely park. Indoor pool, large sites, very well shaded by big trees. Just Lovely. Don't miss Bearazona, the wild animal park nearby. If traveling with children the Deer Park is fun, more for children. From Williams, Sedonna is less than 1 hr away, beautiful, now more of an art colony. Lots of fun for a day. The Wright church is stunning. Also from Williams, just north of Flagstaff is Crater of the Sun, the volcanic mountain range. Lovely ranger station, and some very nice hikes on paved signed walkways. If you have time a day drive (could be a 1/2 day drive but it would be a long round trip) to Monument Valley, and Gouldings RV Park and Hotel. This is such beautiful inspirational country. Words cannot describe.
Happy Trails.