Was just looking through this thread to see if I could get an idea for someplace o go for drinks, and thought I'd add a couple that haven't been mentioned:

• Up & Above Restaurant and Lounge - The Okura Prestige, Ploenchit at Wireless - 25th floor - not a true rooftop place, but a good view and a small outdoor terrace - beautiful setting, exceptional service (even for thailand) - I've only had drinks in the lounge, so can't comment on the quality of the restaurant
  
• Three Sixty Lounge - Millennium Hilton - 32nd floor - not amazing, but they have live entertainment Tuesday through Sunday nights, and good views - a decent choice if the weather is not outdoor rooftop friendly.

I'd love to keep growing the list in the wiki. Any others we've overlooked?