Singapore Gardens by the Bay
First of all, it's a brand new park. One of our Singaporean friends said it was fairly new and had been around for several years. His girlfriend quickly corrected him and said it'd only been around for two or three. Either way, it's the coolest thing. Gardens by the Bay is a huge park containing a solar-celled grove of "super trees" connected by an aerial walkway where you can take in the gardens, downtown Singapore, and the bay area. You'll also find two ginormous greenhouses that you need tickets to enter: the Flower Dome and the Cloud Forest. We visited both, but it was the Cloud Forest that really wowed us.
This is the only way I can describe it: a huge hobbit house covered in waterfalls. It's several stories high and really beautiful. Being the hangry, hot, sore-footed, haze-breathing creatures that we were, it was a lift to the spirits. If you visit Singapore and only have the time, money or foot strength for one dome, do the Cloud Forest.