Not sure if you've done any of these before, and forgive me if any are too obvious, but these are worth considering:
- Empire State Building
- Metropolitan Museum
- Guggenheim
- Eat at Carnegie Deli
- United Nations compound (it's not a bad tour)
- Intrepid museum (aircraft carrier and a bunch of aircraft - not sure if that's where the Shuttle went)
- Some cool bars south of Houston (SOHO) to try out your Aussie accent
- Catch a Broadway show (if there are any good ones on)
- Some good clothes shopping - more for the ladies, but gents prices are also cheap if you need stuff
I thought Central Park was an anti-climax - it's just a park.