Route from Yellowstone to Moab area? Is 191 good?

If you want to avoid the interstate stay on 191 until you get to 60/260, over to Showlow. From there you have 60/77 to Mesa through Salt river Canyon and Globe. Or take 260 across to Payson then down 87. Avoid 191 below Springerville/Eagar since it is the curviest road in the country.
Bikers love it, RV's not so much. The climb out the Salt river canyon is pretty steep but lots of passing lanes etc. other option is across I40 to Holbrook and down through Heber, or all the way to Flagstaff and I17.

Dave