I'll be in Vegas about the same time for a business meeting. Planning to combine business with pleasure, though, I want to spend a couple days at Grand Canyon's north rim (high elevation, relatively cool) and a day at Zion (to hike the Narrows, where it's cool). You really will appreciate your air conditioner in southern Utah during the summer. Fortunately you can see quite a bit from your vehicle as you drive around Bryce and Capitol Reef and Arches. But do try to walk to a few of the arch formations closest to the parking lots, because nothing compares with standing under them or seeing them right up close. (Or running under them, as these kids were doing!)

The views to the east along Hwy 12 between Boulder and Grover are spectacular. I boondocked up there one year, just off the highway, about 100 yards from the edge; a short walk with a lawn chair under one arm and a cold drink in the other hand, and I was all set.