SGS is my favorite pool, but it's small and has limited sun later in the day, hence the water can be a bit brisk when you first get in. I enjoy hanging out in the Sala there with a cool adult beverage and a good book. Food is also good. And if you're a SPG Platinum or book a Grand Deluxe room, you can enjoy free drinks from 6-8pm. WGS gets a lot of afternoon sun, but it's pretty plain otherwise.

Sheraton Hua Hin looks like it has a nice pool. Sheraton Pattaya has several very nice pools.