I'm going to disagree with Marie and say you should definitely NOT do the Extremely Canadian clinic. My husband did that last year and they were nonstop on double blacks, in steeps, in whiteout conditions, skiing very fast and very hard. I went to apres with the EC groups and the consensus was, it's an amazing clinic if you already ski double blacks and you want to learn to do it better. It's not for someone who skis groomers and wants to advance to ungroomed blues and blacks.
As to which mountain, which type of lesson will you do? Privates meet at the bases, so it would probably be easier to do Whistler if you're staying in the village. If you do a Max 4, you're probably a lower level 4, and you'd meet in the alpine of either mountain, both of which are easy to get to from the Village. I'm partial to Blackcomb for lessons because it gets a bit less traffic, and there are some very fun and always uncrowded ungroomed runs on Blackcomb, but really, it doesn't matter that much.