Except for areas with a particularly high number of venues, (downtown, college campus, etc), the shows should turn up in groups based on where they're playing.

Actually, once you get going and have time to start adding features, I'd recommend trying to run some analysis on venues within the search range, and have places that typically fit the search pattern show up on the initial search. Searching for particular shows is certainly useful, but there would also be a lot of times when I'd like to just check out what type of music a place regularly plays. At any rate, it's just something to think about when you get a chance.