Hat Phala, near Rayong. On this beach you will not find many tourist, other than 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. The Thai, generally, do not come to the beach to swim! They come to eat!!
Unlike many other resorts on this coast, they do not charge you here 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.