For me the Amanpuri rooms are not dated but timeless, beautiful and very Thai - or how you would like to think that Thai houses look like while the architecture at Trisara is more classical and could be anywhere. Amanpuri rooms are smaller than the Trisara room, though, and with no private pool (unless you pay a fortune). Agree about the "colder" staff as well, but love beach, spa and gym at Puri. Also food was best at Puri when we were there. This does, however, not mean that food, spa and beach are bad in any way at Trisara. It is a wonderful resort, just I do not manage to choose, so I would always prefer to split my stay between the two.