Normally go to dinner with the fam. Maybe catch a movie if there is anything good at the iMax theatre. Go clubbing with a few friends.
My 21st is this coming Tuesday, so it should be a fun weekend. Still going to the 18-and-up club since most of my group is still under-age. Grab a nice gourmet meal (aspiring chef, so I gots to eat good). I don't know if the iMax will have anything going or not. I'll probably be drunk the whole week leading up to the real celebrations though.