If you have the time:
Zion - 4 to 5 days. You might not get to hike Zion Narrows in the spring due to high runoff. Check with the visitors center. Check out Watchman CG in the park. Not FHU but has electrical hookups and a dump station. Right on the Virgin "River". Walk to the visitors center to pick up the shuttle into the canyon. Easy to return to the RV midday to see to the dogs. Lots of great hiking there.
Bryce - Two full days would generally satisfy us. We do a couple of loops down into the canyon, utilizing the shuttle system so we don't have to go back to the same trailhead. No hookups at the NPS CG's in the park, but high enough elevation and plenty of shade to keep the RV cool all day.
Capitol Reef - One could spend a lot of time hiking this park. Spring is an ideal time as there is little shade on many of the trails. If you don't have a toad, you might decide not to try to get to some of the trailheads, as some are miles down graded, often dusty roads.
Moab - Great hiking in Arches. One can easily spend four or five days. BE WARNED: MANY OF THE ROADS IN ARCHES NP WILL BE UNDER CONSTRUCTION BEGINNING MARCH 1, 2017. The CG itself will be closed all summer, and various trailheads will be closed from time to time. You'll have to plan your itinerary there as you get close to that time to see what impacts there are. Not as much hiking in Canyonlands. Some shorter hikes and some walks out to viewpoints. Maybe rent a jeep for a day and do the White Rim Trail. And check out some of the trails on BLM land. Dogs are allowed on most of them. Negro Bill Canyon a couple of miles up UT 128 comes to mind. Fisher Towers also. If you day trip down to the Needles district, there are some longer trails that are interesting, such as Confluence Overlook. The Joint Trail is also interesting. This might be another place to take a rental jeep to shorten some of the hikes.
Blanding - At Natural Bridges, take the hike down into the canyon to walk under the bridges. You can exit and take a trail across the top back to the vehicle. Some ruins and an interesting panel of red hands down in the bottom. While in this area, also check out Cedar Mesa. There's a visitors center part way down UT 261. Some hikes to ruins in this area, but for most, you need a pass. If you really get into hiking the trails in the Cedar Mesa area, one can spend a week between there and Natural Bridges. One can get to Hovenweep from this area also. Watch for the little gnats there that seem to love Deet based insect repellents. We had more luck with citronella based products.
I would relocate to visit Mesa Verde. Too far from Blanding for a day trip. Don't miss the Anasazi Heritage Center near Dolores, CO. They can direct you to other, lesser known ruins. Try the Sand Canyon hike up McElmo Canyon out of Cortez. The Anasazi Center will have info on how to get there. Between Mesa Verde and these other sites, I'd plan five days. Take several of the guided hikes in MVNP.
Ken & Allison
2 Camping Cats (1 diabetic)
1996 4Runner, TRD Supercharger, Edelbrock headers
2007 Fleetwood Arcadia, Honda EU2000i
4 mountain bikes, 1 canoe, 4 tents, 8 sleeping bags, 2 backpacks
(You get the idea!)