Sheraton Grande Laguna (no more Starwood) was amazing. We were upgraded to a nice Lagoon Villa. Service was great, and every morning they would leave croissants in front of the door. Also they were offering breakfast to Plat long before it became the rule.
Sheraton Grande Sukhumvit is becoming a bit old now but was also for a while one the best stay for Plats (free drinks, best breakfast) and has one of the nicest pool in BKK.