Car-Guy
Give me a museum and I'll fill it. (Picasso) Give me a forum ...
Not for me... But I've been to them all... But if heading that way, I'd add a few more days if that's doable for the OP, especially since he asked for opinions and he's retired... He can always "prioritize" along the way if he likes.Too much to pick from .I do feel the biggest hazard of road trips is overestimating how much ground you can comfortably cover. I'd be inclined to do a Moab area trip with hiway 12 and a separate GC Arizona trip or add a few more days.
Personally, when I take road trips I plan what I'd like to do/see but remain flexible to add or delete stops as my trip plays out. Hard to add stops "if you don't know about them". Much easier to do after I retired than when I worked . YMMV.