If you'll be there in the summer, try to camp somewhere a little higher up. It's pretty hot down by Boulder town and environs. Of course it does
generally cool off at night. We often stay up at Singletree NFS CG. It's at 8000' so cooler. Flush toilets but no hookups. Does have a dump station. I read now that wireless internet is available for $5.
Capitol Reef NP is of course high on the list. The CG there has no hookups, but is in a cool setting in an old orchard. Many of the campsites are double wide, so you should be able to fit in one.
Bryce Canyon NP is also worth the visit. Nice CG's in the park, or stay at Ruby's just outside the gate.
Calf Creek Falls is worth the hike. Don't take your rig in there, I don't know if you'd get turned around.
There are also a number of slot canyons in that area. Scenic, interesting, and photogenic. Check out
this link for descriptions. Spooky and Peekaboo are among our favorites and not to long. But not for those who are a little too wide or claustrophobic. (I wore holes in the rear pockets of some brand new pants easing my way through one place. I know to pay more attention now i.e. take the wallet out!) Dirt road out to the trail head, though, so if you're on bikes . . .