I would add Colorado National Monument in between Dinosaur and Arches. Goblin Valley is an interesting spot worth seeing. If you decide to head down US-191 to Monument Valley, plan on short stops to see the Twin Rocks at Bluff and the Hat Rock at Mexican Hat. Also drive through Valley of the Gods. I've never been to Goosenecks SP, but many rave about the view. Moki Dugway is along that route also... good views.
With your B, you should plan to spend a night at the Navajo National Monument cg (very nice, but small campsites only) and perhaps hike to see some of the ruins. I stayed there with a 17' trailer last summer but I could have fit into only a few of the sites. From there it is an easy drive to GC.
