The Surin doesn’t get very good reviews. Apparently it’s just a Novotel? Not really a luxury brand... (Yes, there is something in between Novotel and Aman. )

I’ve heard that Khao Lak beaches are better, but it seems like there’s almost nothing to do around the resorts? I’m also not sure if they have any good hotels there, it seems like the place isn’t that developed yet.

Any comments on the Andaman/Datai? My father recently stayed in both Phuket, Krabi, Khao Lak and the Andaman (Langkawi) and he said the beach at the Andaman was much better than all the other beaches. He’s not a luxury traveler, so I wouldn’t put much weight into how we perceives hotels, but for a beach I’d trust him.
So I’m still leaning towards that, maybe in combination with Cempedak Island.