Hi Jess,
I agree with Kimbo that Chang is nice but September is right in the middle of the rainy season. If that doesn't bother you then you can fly to Trat (the port where you catch the Ferry from) or catch a bus. I think it took about 6 hours on the bus.
I dont agree with Kimbo about Samet being a dump. In fact , some of the southern beaches are very quiet and clean. I was there 2 years ago and loved it.

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