Are all of the different Native American ruin sites south of the Grand Canyon (Montezuma Castle, Tuzigoot, Walnut Canyon, Wupatki) about the same? Any of them clearly superoir to others? Should we try to hit them all, or are they repetitious?

Montezuma Castle is a cliff dwelling while Tuzigoot is a pueblo-like set of buildings constructed in a river valley. Both were built 1100-1400 A.D. by the Southern Sinaguans. Walnut Canyon, eight miles east of Flagstaff, is a series of dwellings constructed by walling up the front of caves lining the sides of a very steep canyon. Wupatki is a fitted-stone series of dwellings on the edge of the Painted Desert. Each is quite different from the others.

Betweeen Montezuma's Castle and Walnut Canyon, I'd pick the latter (haven't been to the others) if you have limited time. The hike into the canyon was fantastic. Don't let all the steps stop you--it was well worth the effort.

A note of concurrence on Walnut Canyon. It's fairly large -- 2-300 rooms built into a series of cliffs, and you can walk into a number of the rooms to get a sense of their size. Also, the canyon itself is a great setting. Go, explore, and enjoy.

Depending on your available time to visit ruins, all of your suggested ones are worth a look. Wapatki (which would be your most time intensive) is in a remote location near an extinct volcano and the red brick ruins there make striking photos. Montezuma is a quick vista, however, is an impressive ruin. I concur with the recommendations on Walnut Canyon. I was there after a fresh snow in Nov. and it was beautiful. The canyon is picturesque. If there's one to skip, it'd be Tuzigoot-which has been largely reconstructed.