i got in touch with a guy from Prinzip who says they're looking forward to having the gang come by. it'll be 7 euros to get in -- fridays are usually 8 or 9 -- and they have good music and space for dancing as well as some benches and tables to lounge about.
he wanted to make sure we weren't too young (i suppose i sound like i might be under 20), and that we'll come dressed more or less for a club (he probably detected that i'm american!).
doors open just before midnight, and he predicts it'll really get going around midnight-thirty or one. you can mention that you're with the birthday group, but we shouldn't have any trouble.
hope to see you all there!