Garoa is like the Cheers for the cool smart kids of San Sebastián. It's a bookstore where everyone knows your name, or is quick to learn it, and the young, helpful staff can also steer you towards the city's coolest happenings.
With strong ties to the local Basque culture, you can be sure to find an interesting roundtable with a local Basque author combined with a crowd kind enough to translate the important parts for you. On weekends, there are concerts that appear humble on the surface but actually are fairly big local acts in a comfortable, small setting.
Garoa boasts a small selection of English language books, as well as Spanish-language children's books that are too beautiful to pass up. Make sure to stop in the basement, where the project Tako Donostia has its artwork on display (and sale).