I go to Tower on most Fridays. The main problem I have is the bulk of the players there seem somewhat cliqueish, and mostly play pre-aranged games vs each other, or play games other than 40K (on Firday, the schedualed 40K day- no idea what they play other days, could be 40K!)
Long story short, I'd be happy to show up any Friday (or any other weekday) if I knew I was actually gonna have somebody to play against.