Kouremenos is a little gem of a beach close the the village of Palekastro (on the road to Vai) in the north west of Crete. There are a couple of taverna's and a little harbour. Not much is going on, and there aren't that many houses. It's supposedly good for windsurfing (exit "surf beach"). The (sand)beach is the biggest of Palekastro (distance 2km) and it's 1,5 kilometers long. On the south side there is a part that is used as a nudist beach. If you want to escape the buzz of Vai beach than this would be a good option.
Update 2017: the time of nudism has ended in Kouremenos as signs have appeared telling you that nudism is prohibited. Families with small children have taken over.