I think the Trisara special is only up to end of October. They followed Amanpuri's move.

Between Trisara and Banyan Tree I would take Trisara. I haven't seen the inside of the Banyan Tree for a few years now so my information maybe dated.

I really love the inside of the Trisara room. Very spacious and the new plasma TV, bose sound system, ipod hookup, high-speed internet for free (I brought my own wireless router), and good size bathroom makes Trisara the winner for me. The swimming pool is a little more exposed so can't swim around naked. However, you could do that at the Banyan Tree.

Overall, I like the newer facilities in the Trisara and the food is pretty decent.

P.S. Amanpuri does have private pools but only in villas.