Oh I love Singapore, I have so much fun there.
Where are you staying? I recommend the Shangri-La, not close to the track, but a fantastic hotel
Going out I recommend: Zirca, Zouk, Supperclub (go upstairs on the beds), Butter Factory (this place rocks)
Stay away from the tourist traps, they are full of people looking to rip you off in one way or another
Try to go out to Santosa for at least a night, and Holland Village
If you like Thai girly bars, go to Nana’s and the bar in the basement of the hilton (can’t recall the name of it for the life of me)
If you want to see sick red light sorta stuff, Orchard towards (beware: they look like women from far, but are far from women)
tip: find a good cab driver (ask the concierge) and stick with him. the good drivers know where it is happening each night and can take you around, get you into clubs etc.