bear with me as I type must faster in english:
I would not recommend RV, especially for Yellowstone, as the roads are winding and narrow, two-way, not easy to drive. and when you get to your destination, you'd still want to have a car to drive around.
For Banff/Jasper, Yellowstone, snow would close the roads in winter, so the best visiting season is summer, which happens to be family vacation high season, so you'd see big crowds; unless you want to go off season, in that case you'd need to pay attention to road closures - 3 of the 4 entrances to Yellowstone are closed in winter. maybe you could try the shoulder season, like Sep/Oct, when schools have started, and roads are still open - this depends on weather/snow conditions.
Around Yellowstone, certainly Grand Teton NP, and Beartooth Hwy one of the best drives I've been in the country, if not THE best. Mt Rushmore, Devils Tower are further away.
On the other hand, avoid summer to visit the Southwest, as it's too hot. fall is better, personally I love winter there, as there is snow on the red rocks, it could be cold though.
"The Revenant" more reminds me of the landscape I've been in Oregon and Washington, not BC. There are lots of temperate rain forests in these two states.
I love all these places, you'll have a great time :)
HTH.
