well, the way to Dinosaur Nat'l park and Moab from Rawlins is I 80 west to 191 and south through Flaming Gorge and down to Vernal and the east to Dinosaur, but then come back to Vernal and take 191 south to I 70 and then east and down to Moab, and south to Medicine Hat and southwest to 89 and down to I 40 and over to Flagstaff.
But there is a pretty tough descent from flaming gorge to vernal...but we see big rigs doing it every time we use it (going up). If it is hot when you do it, do it easy and let your brakes cool off.