We went to Canada for 2 weeks last August. From Calgary Alberta to Victoria/Vancouver BC across the Rockies. We stayed in Banff for a few nights right at the beginning. The whole experience was complete magic. It'll probably be snowy when you're there? It was hot hot hot when we were there - you can't go wrong whatever.
Loads of places to eat in Banff, very nice town (really just a single strip). No such thing as "cheap" out there though, but not frighteningly expensive. I can imagine it might be a bit poncey with the ski crowd.
Lake Louise we just went for a few hours. Apart from the lake and the other worldly colour of its water, there isn't much there. Unless you're a sporty skiing type I suppose.
Take plenty of film in your camera, as they used to say. Scenery out of this world.
Scenery, animals, plenty of shops on the strip.
We even got to see a Steve Earle concert whilst we were there - and a lot cheaper than when he performed locally in Manchester.
Zipwire was fun too (although my wife couln't be persuaded to try it) : Banff Zipline Tours | Canadian Outback Adventures and Events