Thanks to all for the great information.
Background info I should have given earlier. We are in our mid- seventies in good health but clearly not what we used to be. RV is a 26 ft Born Free with generator and 23 gallon propane tank so think we can handle cold as long as it is not below freezing for too long. Used to driving in snow but not with the RV.
We prefer the freedom of no reservations but from the advice here that may not be possible.
Any thoughts on the route? Original post had starting at Salt Lake and ending at Moab. Any pluses for going the other direction thinking that Moab and Monument Valley tours would be places reservations would be needed.
Again, thanks for all the help. It makes planning so much easier.