i spent 3 weeks in Nai Harn/Rawai and i loved it. but we went in April when there were almost no other tourists anymore
there are only 2 clubs there - one more or less opens when the other one closes - makes planning the evening very simple
first you go to
http://laguna-rawai.com/ and then you go to
http://www.intophuket.com/icon-nightclub-rawai/
unless both get raided by the police in the same night - then you go home
