In Singapore, visiting Sentosa Island is a must see, They added so much since I was there last, They built their first Hotel/Casino The "Marina Bay Sands" and are working on another... Sentosa is home to Underwater World, a man made underwater aquarium where you can walk through it.... You can also sit out on Tanjong Beach, I took the cable car to Sentosa but if you don't mind walking, they have a long bridge you can cross to the island, that is if your staying at one of the Hotels on Orchard Road.... Their also building a Universal Studios theme park there, but it's not completed yet.
Don't waste your money on renting a car, you can get around just fine using the MRT, you'll love how fast and efficient this subway system is, there are also plenty of taxis too, never mind the little bell that goes off in the cab, it's a warning the cab is driving over the speed limit..... Another place to go is the Botanical Gardens, it's not only beautiful, it's quiet and relaxing to walk through. One place I never went was the The Singapore Zoological Gardens, I heard good things about it so you might want to go there too, as well as Jurong Bird Park.
You really should read a travel guide, If there is something not covered, just ask and I'll try to answer.. If you haven't booked your flight yet, I highly recommend Singapore Airlines, extremely friendly and they'll make the flight as comfortable for you as possible.
