Koh Phan Gan has been the beach party island for some years with Had Rin beach at the centre. It is now a recognised "scene". My advice would be to stay at the few bungalows dotted in the trees after Ban Khai Village. I stayed for many winters at Silvery Moon Bugalow run by a friendly family for about a pound a night. Here you can walk around the beaches to Had Rin or call in a passing boat to take you there.

A warning though: Had Rin is very crowded at this time of year and the weather can be unpredictable (I spent a night there in a typhoon). The police are not as tolerant as people may suggest to you - I have met many people who extended their stay in Surat Thani Prison. Having said that its a great place for New Year. The island is beautiful and the people are friendly. But get there early!
David Hatton