I'm thinking about the island which takes you to go, and then September to November. We should not go to the South is the monsoon. It rains a lot.
Therefore, the I think we should not go to Koh Samui. In this year.
I think that will take you to Koh Samed instead because.
1. I can leave the work few days . we should to go koh Samed more than koh Samui
2. travel will be easier.
3. Koh Samet is located in Rayong province. I think that it will rain less.