Stop me if you've already heard this, but I just found out about a very cool site via a favorite librarian blog. Cinema Treasures is focused on all those classic movie theaters that are (or were) in operation around the globe. There's even a theater guide in case you wanted to check out what there is to see when you go traveling. Check it out. There are entries (naturally) for my two favorites, Coolidge Corner and The Brattle with a really active set of comments on each!
Of course, if you already knew about this site, don't I feel stupid?