For a honeymoon I highly recommend Baan Taling Ngam resort. It is now an Intercontinental property but my wife and I stayed there just over one year ago. It's in a very quiet corner of the island and the food at the resort was amazing. Great spot for a quiet and romantic getaway.
Not sure if it is still available but they do nightly private dinner on the beach for one couple. you have to book this a bit in advance but it is quite special.