I found downtown Flagstaff interesting, tho' I just walked around for an hour in the early AM before the shops were open. I was waiting for Lowell observatory to open (also in Flagstaff; worth the effort).
There's a big museum in Canyon, about 15 minutes south of I-40 in Amarillo.
http://panhandleplains.org/pages/about_pphm_29.asp. I spent a full 1/2 day, mostly just walking by the exhibits & snapping pix. There's a full-sized 1920's oil drilling rig off the lobby, to give you an idea of the scale of the place.
There's also the Painted Desert / Petrified Forest between Flagstaff & the NM border. I spent a day there, taking a few walking tours.
Jim, "Everybody seems normal, until you get to know them."