Singapore is such a busy yet tranquil place to stay, my wife, 3 daughters and myself went for 3 weeks a couple of years ago and have to say it was probably the best place we have ever had the pleasure of travelling to. No grafitti, no homelessness and alcohol abuse is very very limited on the entire island.
The Singapore Zoo is a full day out, the boat trip and night safari in the zoo are both well worth it too.
Chinatown has some fantastic eateries and souvenir shops. Chinatown is by far the cheapest place to eat and drink, anywhere else is pretty much twice the price. Alcohol is extremely expensive everywhere else too.
Universal Studios and Sentosa Island as a whole is pretty good also and again you could take the boy on most of the rides and take most of a day to get round Universal Studios alone.
They celebrate their National Day on the 9th August iirc, we were there for that and the jets flying in round the high rise offices in the business district is just awesome, the noise and vibration is frighteningly intense along with the chinooks and other aircraft, they also parade all of their tanks and heavy moving army gear.
Raffles Hotel is a must just to sample the Singapore Sling cocktails, they are ****in expensive though, around 100 quid for 7 drinks, 3 were alcohol free.
The Marina Bay Hotel is simply fantastic to behold, it really is a work of art and while you are there you can see the F1 track being laid out at some parts.
Are you going via Dubai and Sri Lanka? If you go through Dubai and have a load of hours or a night lay off, you have to go to the Atlantis on the Palm hotel, the restaurants and massive, and I mean MASSIVE water aquarium is simply staggering.
This pic is only a small part of the thing, something like a dozen restaurants back onto the tank and they have something like 6000 fish in it.
I took hundreds of pics on the 3 weeks we were there, heres a few.