I'm not a Singapore expert, although I have spent a few days there and really loved it. It reminded me of being in the Hawaiian Islands -- warm and lush.

I noticed that no one has mentioned Sentosa Island. That was my favorite place to visit, and I went there twice.
>From memory, there were two ways to get there -- either by boat (a very short ride) or by cable car to the top of the mountain. The cable car station is on an upper floor of the tall building at the cruise terminal. That's the way I traveled back and forth to the island, as I was staying on a cruise ship. The views, gardens, and fountains are lovely, but they also have a wonderful museum. Be sure and allow a lot of time for the museum, as it covers so much of Singapore's past -- the different cultures (with wax figure settings), as well as the occupation by Japan during World War II. There are also gift shops if you're into shopping, and also hiking trails if you want to do that. http://www.sentosa.com.sg/

Regards, Diana in San Diego, California