There's a Relais and Chateau - Post Hotel - near Lake Louise that's nice.

Also the Canadian Pacific Hotels - Chateau Lake Louise and Banff Springs Hotel - are lovely.

If you want to consider some place else, I preferred Moraine Lake to Lake Louise. The Moraine Lake Lodge there is nice.

Good luck finding a place. I was there last year at this time and we had trouble getting hotels five months out. Hope for cancellations.