If you like camping, hiking and nature, old temples and hill tribes, and want to experience the REAL Thailand, I’d recommend visiting the cities of the north: Chiang Mai, Chiang Rai, Lampang, Pai, Mae Hong Song. Of these, Chiang Mai is the most “touristy.”
If you want to see hilltribes, please read this article from Welcome to Chiangmai & Chiangrai magazine first:
chiangmai-chiangrai.com/ecot … endly.html
It’s a good overview of how the people have been exploited for tourist dollars and how to choose a responsible hilltribe guide.
For the beach thing, Ko Samet is fairly easy to reach from Bangkok (3 hour bus, 30 min. ferry). You’ll encounter crowds and annoying peddlers if you stay on the northern part of the island. The best beaches on Ko Samet are further south–I stayed at a resort on Ao Wai beach. You can get straight to Aoi Wai by a ferry from Rayong, otherwise prepare yourself for an expensive songtheaw ride over an extremely bumpy unpaved road. Gorgeous beach, lots of sand and shady trees, MUCH quieter than the other beaches at the northern end, excellent food at the restaurant. It cost about 900 baht a night, but of course that changes with the season. One sad thing you’ll find on Ko Samet (and in Thailand in general) is a lot of littering. You’ll find a lot of little trash-filled crags along the rocky parts of the shoreline that would otherwise make good picnic spots.