I'd highly suggest having a rental car around Lake Louise and Banff. Part of the fun is driving around on secondary roads to see wildlife, additional lakes, the glacier, etc.

Be sure to set expectations. The Fairmonts might be the best options in the area, but they're huge hotels with tiny cookie cutter rooms (for their standard room categories--I had a lovely specialty suite upgrade at Lake Louise) with lots of discount bus tour traffic. The breakfast buffet was a zoo with long lines and servers not able to keep up with either restocking the food or clearing dirty dishes. Still, the setting is special.