Jasper Park Lodge is also my favorite, but I think lots prefer the Banff Springs. I like JPL for the cabin feel, and just prefer the Jasper area better in general!
I LOVE the Whistler property in Winter, there is nothing better than having a Corono in the outdoor hot tubs. That being said, I am also a big fan of the Whistler area in summer, so it is a tough decision! I would probably do the Vancovuer/Whistler thing, and then hop on a plane and fly to Calgary or Edmonton (westjet or Air Canada are your 2 options), and then do the rocky mountain circle (Calgary, Banff, Lake Louise, Jasper, Edmonton - or vice versa).