Super Rich
There is a Super Rich outlet at the Chidlom BTS station (InterContinental hotel's side) and another (kiosk) inside Big-C on Ratchdamri but both don't have as good rate as the only two blocks from Big-C ... yesterday exchanged U$ for a 34.03 Baht rate which is great considering all other banks' around 33.70.
Haven't had the need to use an ATM yet and will try to keep it that way.