I stayed at Banyan Tree last year. It's a dated property and in dire need of a refresh. Location is meh, the traffic is forever gridlocked. I was even told by my taxi driver to get down and walk the last mile back to hotel as we were stuck in a massive jam.
Movenpick BDSM is a nice property off Sukhumvit road with refurbished rooms. I prefer it to Banyan Tree. It's certainly not as "cookie-cutter" as a Novotel.