It's a Marriott, it's upscale, and it's been described many times before. The pool, breakfast buffet and restaurant, and the beach are wonderful. You may also want to know:
It is a bit far from "town": Khao Lak is an 8-km drive and local taxis have decided not to accept less than THB 300 each way. The hotel shuttle is a bit less expensive (THB 100 per person per trip) but it runs only every two hours from 11am to 10pm.
The good news is that the restaurants and massage stands on the beach are quite all right, if you are fed up with the resort but don't want to spend a meal just going into town.
The hotel is mid-way between Tap Lamu and Baan Nam Khem piers (not in kilometers but in road time). These are the South and North piers that dive operators use. As always in Thailand there are many more dive shops than dive operators in Khao Lak (the former buying and selling spots on the latter's boats). It matters because Khao Lak is such a big diving destination. Below is a brief outline, I'll review those I have dived with separately.
- Sea Bees have a shop and representative at the Marriott. Unfortunately they have had trouble with the contractor that built their new catamaran and it has been highly unreliable. Check on site but it doesn't matter as they still have to drive you to one of the piers.
- Khao Lak explorer have tried the usual "buy a cheap shipping boat" thing but the sea here can be more choppy than in the gulf of Thailand AND the distance to the Similans is too far for a day trip at 6 - 10 knots
- Similan Seven Sea Club have a very well oiled routine, pick you up on time, get a speed boat at Tap Lamu and transfer you to their liveaboard on site. It makes for a very nice day out diving (and you can also stay one, two or more nights on their liveaboard, the Camic, though the cabins are getting a bit old). SSSC depart from Tap Lamu, which is on the other side of Khao Lak, meaning a lot of stops on the way as you are picked up first. If only for that reason you may consider the next one.
- Big Blue Diving is a local branch of the huge Kho Tao dive center. They have the fastest local speedboat, which leaves from Baan Nam Kem up North where you can also see the 2004 tsunami memorial. The pier is further than Tap Lamu but the drive is about the same time, plus you are getting a bit closer to Koh Bon and Richelieu Rock. A good choice especially from the Marriott.