Stopover for 4 days in Bangkok

Hi!

in september we are on a trip from europe to taiwan. we do fly via BKK
and have chance for a stopover from saturday afternoon (arrival in
bangkok airport) to tuesday afternoon (departure to taipei).

Any suggestions for a relaxing stopover destination that is:

a.) beach

b.) with facilities but not too touristic (e.g. I did not like
phuket/krabi/phi-phi too much)

c.) easy to reach from BKK airport so that we do not spend too much time
traveling to and from the site

Any suggestions?

manfred

p.s. I know that it is well worth to stay 4 days in bangkok but I'd
prefer beach instead of city ...