That's a lot of beach time? I'll just toss in 2 cents about Hua Hin--3 hrs south of BKK. We're not touristy beach bums (and older--50ish) so it satisfied a break from Bangkok--historical/cultural, small/fun/hip low key beach town. We also liked Kanchanaburi (Kwai River) just otuside BKK the otehr way.