There is not any dispersed camping in Capitol Reef.
There is lots of 'designated' but dispersed camping in Canyonlands - you need a permit, but I think this is the best of both worlds, you are guaranteed that a camp spot is available for you and is off on its own, and they are reliably great spots. No competitive campground hunt as dusk approaches, no bogans with generators and ATVs pulling up after dark, and without the dozens of spurs and fire rings all over the place like in the nearby BLM.
Great Sand Dunes NP has some dispersed camping on the Medano Pass road (technically in the preserve, not the park, but managed about the same).
Most of the SW National Monuments (GSENM, Bears Ears, Vermillion Cliffs, Gold Butte, Grand Canyon Parshant etc) also allow dispersed camping.