I just got back from 2 weeks in San Pedro over the Christmas and New Year's holidays. Wowza, what a party scene it was! On the dock area, Dnoz is good food, the new pizza place run by true Italians is great, and Allegre Pub is a friendly place to hang. Freedom had a great Christmas Eve party that went til 3am.
On the 'other side' of town is where the bigger parties happened--the new Buddha Bar/ Restaurant has the best chef in town, and the owner, Mike, has really created a hip Asian atmosphere in his 'zen lounge'. But the big events there are the Sunday night parties--the one I went to on Christmas day was totally packed, and I heard it went til 4am on the rooftop dance floor. I went back there for the New Year's party, and obviously, everyone in town was there because you couldn't breathe, it was so packed. They had built this huge video screen on the roof for a video DJ, to go along with the music DJ--it was awesome! I stumbled out at 6am, and it was still going.
San Pedro is a great place and seems to have become a new stopping point for Central American travelers in the last couple of years--just remember to pace yourself, since it is really easy to visit for a few days and stay a few months. That would be really dangerous to your liver--did I mention that this place is dirt-cheap!