I have never been to either Dinosaur NM or Flaming Gorge, so I would ask one of the others about that route. I have been to Colorado NM several times, however, and it is mainly a 19-mile rim drive with views into the canyons below and some nice rock formations. The Coke Ovens and Independence Monument come to mind as two of them.
I can recommend the second route as the scenery along it is good all the way. Logan Canyon and the overlook above Bear Lake are really neat. You might even take a short side trip into Salt Lake City to visit Temple Square, an impressive place.
Either route should include the drive up UT128 from Moab along the Colorado river to I-70 at Cisco, UT. It is one of those three scenic drives I mentioned in an earlier post and shouldn't be missed.