Bob Kattner and I visited a few of my favorite spots in the area in early October. If you never visited any of them, we highly recommend visiting them.
Utah is my favorite state (at least the southern third, home to five national parks and several national monuments). Had my great grandfather been one of Brigham Young's many children, I might have lived there--rather than milking cows as a youth 730 times a year in Newton.
Northern Arizona is on the southern fringe of the Colorado Plateau. We saw a truly magical place there--Antelope Canyon. It is on Navajo land. We also saw Horseshoe Bend, an enormous twist in the Colorado River. Both places are very close to Page, Arizona, which was built when the Glen Canyon Dam was constructed in the late 1950s.
The only thing we saw in Nevada was Valley of Fire State Park, just off I-15, an hour from Las Vegas, on our return to the airport.
I remember in grade school looking at pictures of Utah, impressed with the colorful rocks. Never have I been disappointed in visiting there. The variation in color, in rock formations, and in vegetation (or lack thereof) keeps me from boredom as I travel through lower Utah, and into Arizona. I think you'll find the same when you go there--and I hope you do.