Make sure they're open over Christmas time too. Everything was shut down 24th-26th when I was there. (well, stuff was open 26th, but there's a massive parade, and it's virtually impossible to engage in any normal activities.)
I was actually staying in (the town of) Heredia up until the 23rd, but with the Uni out of session, the town was totally utterly dead (or so the hotel owner told me. I was the only guest and they had at least 20 rooms.) I moved down to SJO because at least there were other hostel guests there to keep me company -- including a surprising number of fellow Panthers fans.