For near the airport, check out Nai Yang. I originally went to stay one night after an evening flight arrival, and ended up staying their for three nights. Lovely beach, not crowded (and I was there peak season), a good selection of restaurants / bars along the beach (tables in the sand) and either part of or adjacent to a National Park. Accommodation wise I stayed at the Nai Yang Beach Resort, which is a simple bungalow outfit, but perfectly good when you're just sitting on the beach all day. There were hotel oiptions there too.