I've driven out to Utah over a couple dozen times and every trip I see something different. I guess what I'm saying is relax, take your time, don't try to see it "all" cause you can't. Just pick a section of the state and hang out there, if you try to see too much you'll spend all your time driving. So with that said, do you have an idea of what part you're thinking about? San Rafael Swell is pretty nice, but hot in summer. Grand Staircase is my favorite area, but again, it's hot in August. Also, August is the monsoon season, and many roads are impassible when wet, so keep an eye on the weather. Flash floods are no joke. Maybe Cedar Breaks area? It's got some altitude for cool temps and isn't so bad when it's raining.