Gu's Bay

Under a friend's recommendation, we left the noisy Sea Flower Resort on Lonely Beach and moved a 30-minute walk south to Gu's Bay in Bai Lan Bay. It can be booked online via agoda. By songtaew, it's a 3-minute 50-baht ride from Lonely Beach to Bai Lan Beach. It's pretty quiet most nights except for Saturday, when you might hear parties in the distance with loud music playing until 4 am.
The grounds of this lovely place is a 3-minute walk from the fairly quiet "main road" which has a few shops, massage places, and restaurants. It's situated on a rocky beach - quiet, beautiful, and relaxing. The nearest beach, Bailan Beach, is about an 8-minute walk away, with brown sand and occupied by by three resorts.

The swimming pool is 24-hours and just in the perfect surrounding! Internet quite frequently gets cut off then comes back on shortly after. Wifi is not the fastest and can only be used in the restaurant/bar area where there is a pool table (20 baht) and a TV playing movies occasionally. Food and drinks range from 50-100+ baht, pretty reasonable for Koh Chang. The rooms may look a bit dated on the inside but are decorated with an artsy vibe.

Bai Lan Bay main street

side street to Gu Bay

The smaller fan-room is 500 baht a night. We chose to stay here a week. There are no screens on any of the windows, but there is a mosquito net over the bed. Aside from many bugs that are commonplace in the tropics, we had 4 cockroaches in our bathroom during our week-long stay. It's quite hot inside the room but not too bad if you sit directly in front of the wall fan. On the ceiling, there are some black spots (mold?). We could feel the springs of our bed so it's not the most comfortable. The shower is not amazing but it's okay temperature/water pressure-wise. No wifi in the room.
The slightly bigger fan-room is 650 baht a night.
Air-conditioned bungalows are 1200 baht a night.
To be honest, I'm not crazy about our room, as it's very basic and pretty hot inside. However, outside the room, it's absolutely gorgeous! You can literally just hang out here all day and not go anywhere else - nice sunset by the way. Because it's right by the ocean, gentle sea breezes cool you down even during the day. There are two huts with chairs and hammocks to relax in.

The open restaurant/bar area is further ventilated by quite a few ceiling fans and have comfortable cushions so you can lie down and read or watch the movies they sometimes play. At night, you can chill in a seaside hammock, listening to the tranquilizing sound of the ocean, watching coconut palm fringes sway in the wind with star-studded night sky as the backdrop - in a word, it's heavenly.

If you want to stay at a nicer room, Seabreeze Resort near Kai Bae Beach might be a good option. If you want to be closer to bars and parties and don't mind loud music at night, Sea Flower Resort is a 10-minute walk to Lonely Beach.