A little off the "beaten path" (20 miles from Brice NP), but well worth the visit. Feeding the local partridges was one of the highlights of our visit. Two excellent hiking trails. Overall, we have found Utah state parks to be excellent.
We don't have ATV"s, but we enjoyed our 1-night stay on our way to Bryce. The coral (pink) sand dunes are a sight to see. If you have ATV's, you should definitely put this campground on your list.