If you don't get the responses you want, I can move this to "RV Parks, Campgrounds and Attractions" where people talk more about the destinations instead of this forum where the posts focus on the specific highways and interstates to get from Point A to Point B.
As for your question, how much time do you have for your trip? More time means more destinations.
My kids went to college in WY (UWYO) and winter can come really early there. I've seen snow in September there. And the wind is a constant all year round. We had a wind storm hit us in September and blow one of the windows out of our fiver's bedroom.
It's a gorgeous state though. Lots to see and do. You just have to be patient and flexible. Be ready to quickly change your plans when the weather changes.