Yes indeed, the Rocky Mountains are HIGH! We've just completed a month long trip to Glacier National Park in Montana and Banff National Park in Canada. Along the way, we also stayed in Las Vegas, Salt Lake City, and Calgary. We had a fabulous trip and I will be sharing reviews of the Marriott hotels, national park lodges, and bed/breakfasts where we stayed. I will also write reviews of our favorite activites and restaurants. Of course, I will also share some of my favorite photographs that were taken by my husband. It will probably take me a few days to complete all these reviews; however, if you are planning a trip to this area and would like to ask me questions, please do. I'll be more than happy to share my opinion.
I did that trip in pieces, Glacier National Park & Yellowstone & Tetons in one and Canadian Rockies in another. For both I was unable to find Marriotts. From your list, it doesn't look like you did either. Both had a lot of beautiful scenery. I had good weather for the first and so-so weather for the later. I enjoyed them both. Will wait for pictures!
You can rent a car. However when I went I used a transportation service recommended fy the Fairmont hotels,
Brewster Transportation: 1(800) 661-1152
They will take you from pt A to pt B as transportation or as a sightseeing tour. If you choose the later, they take your luggage and make sightseeing stops along the way. I was happy with them.
I went from Calgary to Lake Louise to Jasper to Baniff and back to the Calgary airport.