Ghost,
I agree with legov, 5 days is a ton of time to be in Singapore, it is a very very tiny island. I lived there for 16 years and dreaded it and was glad to move out. I do like to visit but not for that long, 3 days is enough, you can get around the city very easily with public transport or taxi. It's so freaking clean you could lick the floor....well maybe not. Food is incredibly inexpensive however booze is incredibly expensive lol.
If you are into photography it is a lovely place to go, if you are into partying it does have a huge scene but again it is pricey, if you like to try new foods then you cannot argue that Singapore has the widest and probably best food in the World...yes bold statement but that's the general consensus from a lot of people who visit there!
Have fun no matter what but....make sure you do not mess around with the cops or the law, they are really really stingy with that.