We stumbled across A. Mansion haphazardly, not knowing what to expect, and were quite happy there. The lobby was very nice and we asked to see the rooms before checking in. We were shown two rooms. One was smaller, with A/C, reeked of cigarette smoke, and cost 500 THB. The other was much bigger, with A/C, and the air was clean and clear, for 600 THB. We went with the second choice. The king sized bed was one of the softest we'd slept in during our extensive travels in Thailand. The A/C worked well. There were two free bottles of water, toiletries in the lovely bathroom (which was almost a western bathroom, minus the shower curtain - though there was a shower rod!), plenty of shelving and storage, decent free Wi-Fi that reached up to our high floor room, a very affordable minibar with snacks and food, a fantastic breakfast restaurant next door, quiet, near fun places to play and eat. We were happy and we will return on our way back from Koh Lanta.
