Ok so I've been in Banff for 3 seasons now and if your looking for a chilled out vibe it might not be the place for you. Its mostly filled with people who want to go out and party, get rowdy so at times it can be hard just to kick back and relax, especially if your planning on working as an instructor and living in staff accom to save money? The resorts are great, the park at sunshine is usually solid and its been getting better at the lake and hopefully they can properly step it up next season.
The mountain at Revelstoke is intense, the snow is often good and when it is its a ridiculous resort! However when it misses snow and gets icy it may be the worst place you could ever ride! As for the town its pretty small not a whole lot going on, for me it would be overly isolated but depends what you want. Also after speaking to instructors they really don't make enough to live on, it's not that type of resort so expect to need a second job.
I don't know much about Whistler apart from it's expensive as hell and next year could be a shitshow for the olympics and the amount of people there!