My brother and sister-in-law married at Ting Rai Bay Resort in 2011, hiring the entire resort for all the guests for a week.
After spending 2 nights in Ao Nang, arriving in Tai Rai Bay via a ferry then long tail was like entering a blissful oasis - no more crowds, hawkers, noisy bars or busy streets. Peace!
The rooms are comfortable rustic huts of varying sizes, some very large with multiple beds and very large balconies suitable for families. Others like ours was small but had two big chairs with cushions and somewhere to put your feet up. Inside the rooms are rustic but if you're not expecting 5 star facilities you should be pretty happy. Our bed was comfortable and had a double mosquito net. There was a small desk, chair, lamp and something to hang towels to dry on. Fresh towels and bed linen are provided each day which was a relief as in April when we were there the intense humidity meant nothing ever dried out completely. The ensuite bathrooms are very basic - a small sink, handheld shower, large bucket (handy for washing your clothes in), no hot water (there is just one room in the resort that has hot water and air conditioning and I'm guessing it books out fast!). Some basic toilettries were provided but I would strongly recommend taking your own soap/shower gel, toothpaste etc. Everything is very clean. Each room has it's own balcony with seats where you can watch the world go by. Our room was situated fairly near the bottom of the hill (second hut from the bottom) so were lucky we didn't have much of a climb as the hill the resort is based on is quite steep.
We stayed for 5 nights and ate some of the best and cheapest food we had in Thailand in the resort's restaurant. The bar selection is pretty limited - beer was the main beverage of choice and we brought wine with us for the wedding as they don't sell it there. I don't recall there being any cocktails or spirits offered, but I could be wrong. There is an endless supply of cold water (large bottles).
We didn't explore the entire island but from walking up and down the beach it looks like Tai Rai Bay has the best beachfront as they have deliberately cleared it of the many rocks that otherwise line the shoreline, making swimming safe and relaxing. The resorts has 4 or 5 cabanas. They've probably seen better days but were fine - we picked up some grass mats from Ao Nang which came in handy lying on the beach or on the cabanas huts. There are hammocks and wooden beach loungers around, so there is usually somewhere comfy to lie down or relax. The resort owners and staff are honest, friendly and helpful.
Really enjoyed our stay there. It is a little on the rustic side and the lack of hot water meant the next hot shower we had (at the Hilton, Bangkok) was long overdue! However it was incredibly peaceful and relaxing, perfect if you want to get away from it all, are on a budget, and don't want people hovering over you trying to sell you something every 5 minutes. Take some good books to read and a torch/flash-light will come in handy after dark. There are no shops nearby so if you want snacks bring them with you.