We drove from Maryland and back this summer basically doing your trip in reverse in 3 1/2 weeks. Three months would have been a cake walk. Our trip found us traveling 6,395 miles through 17 states, visiting 10 national parks/monuments, and 2 Native American Tribal Park. We did have some long driving days, but the parks in southern Utah all quite close together. We stayed in the same campground for Arches and Canyonlands.
We are not hikers so our visits to the various parks did not involve time for hiking. The trip is documented in the blog Arches, Geysers, and Canyons in my signature.
We did not visit a number of places on trailertraveler's list as we have been to those in the past.