We have spent four days in Marriott Rayong and would return for more. It is a big hotel with over 200 rooms, yet only occasionally we could tell the hotel accommodates that many guests. Rooms are spacious, very well designed (kudos to anyone who designed the entrance/bathroom area and bay windows), beds comfortable. Views (we had the sea view room) were outstanding (especially at night, when fishermen were working by the sea). Facilities excellent (one large and one smaller pool, close to the beach which was super clean and spacious, several cafeterias / places to eat). Breakfast service best in the world. Staff friendly and helpful (Jeab, you have made our day, thank you!).
The biggest advantage (for us) was that the place was quiet, with no loud animations or parties, far from the noisy city center and the street. Perfectly relaxing environment.