the two best hotels by far are the Banff Springs, and the Rimrock:
http://fairmont.com/banffsprings/
http://www.rimrockresort.com/
both are absolutely great hotels, though the Springs is much, much larger (and older) - basically it's a castle. However, you can't beat the views of the rimrock, it's situated on the edge of a cliff, be sure to get a room on the cliff side if you stay there, unless you don't really care about views. I also think the service at the Rimrock is better, and it has a much more remote feel. Really, you can't go wrong either way. one thing to consider is that it's about a 3 minute drive up the mountain from Banff to get to the rimrock. Where as you can walk to main street from the Springs. i can try and dig up some pics...