Hard to go too wrong, may be starting to get hot. If you are heading into canyonlands NP there is a dirt road, Lockhart Basin I believe, that leads to a primitive campsite (s) and many places to camp. Stream down there a couple miles that is nice. All sorts of possible exploration. If hot head up West of Monticello, a couple high elevation campsites I think on County 101, only road. Also lots of camping in Valley of the Gods, or on the river by there at Sand Island, or above o the rim, others have mentioned places there. Natural Bridges is cool, near Goblin Valley the dirt heads N all the way to I70, anywhere through the San Rafael Swell. Near Arches camp by the Colorado River, up or downstream. Of course Bryce and Zion, also Capital Reef. The developed campsites are of course busier but fine.