US 550,
(the Million Dollar Highway in 10 minutes) is a frequent discussion here. A beautiful not to be missed drive. But in an RV? Some say "no problem". Some say "no way". I would only say do it if you are very comfortable with mountainous driving and your rig is in very good condition for it.
It is a steep, narrow, winding highway without shoulders and guardrails. And it is a long way down the sides into the valleys and canyons below as you can see from the video in the link above, although the video really does not do it justice. Three passes, one over 11,000 ft, one over 10,900 ft.
You can turn west at Ridgeway (just north of Ouray) on US 62 to CO 145, the south to Cortez, and then over to Durango to miss that worst part.
US 160 on the other hand is an RV pipeline across southern Colorado. There is a constant RV flow both ways all during the prime travel months. Wolf Creek Pass east bound from Pagosa Springs is a pretty good pull but it is a very good highway with two lanes going all the way up so you can take it easy in the right lane and let traffic pass in the left lane.