Dont know about RVs but we were in Mt and Wy last year (road trip in 4wd) and they are SPECTACULAR! My DSs (9 and 11) coped really well with the driving, the roads are empty and well-made and lots of rest areas.
I looked at the route in minute detail on Google maps, looked up all the little sights/monuments that are marked on there, and looked at the satellite view. Broke up each day into 2 hour chunks and found things to do , places for a wee and a coffee, etc.
Butte, Mt is well worth a day or 2 to visit the mining museum and see the lovely town.
Help! I'm in the first stages (just thoughts really) of planning an RV trip from California to the Carolinas with Montana/Wyoming on the way. Will be travelling with hubby and two girls, by then 8 and 5. Does anyone know if would be cheaper to hire or buy an RV? What unmissables are there along this route? Everything is open to suggestions!! thanks!