"If it were me, I'd just take a taxi or bus to Hua Hin, which is the closest beach to Bangkok that's pretty nice (and isn't crazily built up like Pattaya, where the beach isn't that good anyway)."................ IMO, the beach in HH "isn't that good anyway", but it makes the most sense given the time frame. The beach in Pattaya is a cesspool. Nobody w/half a brain swims in it. One could take a boat from Pats to Koh Larn or Ko Samet and get there fairly quickly though. Does the 7000B limit include hotel, airfare, taxis, food & drink ? If it does, Hua Hin - Cha Am or Koh Larn might be your only viable options. HH is a great little beach town with Thai flavor and good food. The beach is just OK. Koh Larn has great beaches, seafood, snorkeling, and little else. If the budget is bigger, we can talk Phuket, Samui, and Krabi.