visiting thailand (Bangkok)

hi all
i am coming to visit thailand from middle of july to the first week of august
with a friend of mine, we are planning a trip from bkk to the north and then go down to ko tao and ko samui to relax.

does somebody know a nice place to stay in bkk and ko samui? offer is so huge that makes the choice impossibile

if someone is there he/she is more than welcome for a drink with us!
thanks a lot
guendalina