Hi Aruni,
It difficult to pinpoint ,what I liked most. I love Thailand and the people. Thai food is awesome . The places are very clean.
Every month on the Full Moon day (dates are provided for people to plan the trips) there is a Party on the island of Koh Phangan…30 mins biar ride from Koh Sumai. The party starts evening around 7.00pm and goes through the night by the Beach. People from all over the world come for this. About 20,000 people come here for the party. Whole island is in party mood. Entrance fee is 200 Bahts. You can buys drinks and food from the carts, vendors or 7 eleven shops all over. Yes, it was a great party to celebrate our 40 year Reunion.
You can more information on YouTube videos and Google!!!
Regards
Dinakar1