Hat Phala, near Rayong. On this beach you will not find many tourist, other then Thai. If you want quiet, this is the place. The beach area is clearly divided into recreational and place for fishermen activities.
There are several restaurants, which will bring you food under the umbrellas.
Unlike many other resorts on this coast, they do not charge you anything to rent the chairs and shade. I think the guest houses are reasonably priced, but since I only came to spend a day there, I did not ask.