As well as the big aircraft graveyard at Davis Monthan near Tuscon, there are loads of airliners stored at Marana, between Tuscon and Phoenix, Mojave and Victorville in California, Goodyear, just west of Phoenix and Kingman in the northern Arizona desert (on the old 'Route 66')
The only one of these I've been to is Kingman. There's a nice aviation themed diner in the 'terminal', and quite a few operational old aircraft as well as the stored airliners. When I was there, there were a couple of DC6's in for maintenance and I was allowed to have a look round inside one. You'll probably pass close to Kingman on the way to the Grand Canyon or Sedona. Worth a stop perhaps.
As FFF says, the area around Sedona is stunning. I've visited by car but not by air. It's at the top of my list for next time.
If you're on the California coast I once stayed in a little town called Oceano (about 100 miles north of LA, near Pismo Beach). All it has is a little airfield and miles of empty beach. Our motel was just off the end of the runway. That was before my flying days, and watching someone having a flying lesson there was one of the things that inspired me to learn to fly. I plan to go back there sometime too.
Wherever you co - take loads of pics and post them on the web with a link from here.