I disagree with Tony (what a surprise). :lol:
Banff: no need to rent a car / convient shuttle.
Mammoth: don't think so and the place is so much more car oriented. Not as close to an airport either.
Banff: you can stay litterary on the hill at Sunshine. If you decide to stay in town, shuttle buses to areas are great.
Bored? Well Tony and Adam might get bored at Sunshine, but heck how many ski areas have they seen all over the World? They look down on the East and I wouldn't even venture and they would think of Midwest skiing? This said, you don't have to ski one week at Sunshine? Sunshine will pretty have great coverage on Lookout mountain.
Here is my breakdown of days at both on my two exclusive Banff week trips (both in April)(not counting my combo trips in 96 or 02):
Yes, I prefer LL, but SV is far from being a terrible place to ski.
Lake Louise: 6
Sunshine: 5
Sunshine is the only ski area I've visit in North America that has that Alps feelling/vibe. Skiing above treeline, scenary, etc.
About being bored with Sunshine (okay, this was March break), but a ski industry/ex-racer guy (I'm not in his league) and his racer kids spent one week at Sunshine. Don't think they were bored.
I also love Banff, but I don't think the access is as easy, though there are many amenities. You would need to take a shuttle or rent a car to get from the airport to Banff, and then from Banff to either Sunshine Village or Lake Louise. While they stay colder longer than most BC ski areas, conditions can also vary as they will anywhere that time of year.
I commented on the car part already. Banff is colder, winter last longer. I've had winter conditions with winter snow as well as Spring conditions on the trips I've had at Sunshine/LL.