The hike that stands out in my memory, is in Yoho.
Take the shuttle bus to the Lake O'Hara Lodge. Unload. Gawk, stunned with mouth open. When you've stuck the eyeballs back in your head, hike up to the Abbot Pass Hut on Mt. Victoria. It was BEAUTIFUL. I posted photos under my profile (fyi).
You might want to check out hiking to the Stanley Mitchell Hut, that was pretty cool, too. Not as jaw dropping gorgeous, but a very decent hike all around (especially if you are interested in glacier moraines).
A hike I never did, but heard was good, is going to the Moraine Lake Lodge.