In the Arizona and New Mexico region I would add Chaco Canyon, Ship Rock, and Monument Valley along with the south rim of the Grand Canyon as these can all be see without a lot of detours.
The southwest portion of Colorado around Durango and the San Juan National Forest. Going from Durango to Telluride is some of the most beautiful country I have seen anywhere in the USA. If given a choice of this area or Utah and Arizona I would opt for this part of Colorado without a second thought.
Santa Fe and Taos are two special places that I would not want to go the western USA and not see.
For California the book on California Camping by Tom Steinstra is a great resource.
When traveling from central California to Arizona and beyond we always avoid the Los Angeles area and go through Tehachapi instead. A fraction of the traffic and none of the smog (except around Bakerfield) and better scenery. Great little RV park with full hookups at the glider airport in Tehachapi.
In terms of wine country I would bypass Napa/Sonoma and instead include Monterey and San Luis Obispo counties and the Paso Robles area.
In Northern CA there is Lassen Volcano NP and McArthur-Burney Falls and Prairie Creek Redwoods State Park that are on my must see short list for California.