1) Congratulations.
2) What days/time of year are you coming? Lots of different things going on at different times of year.
3) Helicopter tour! For around $200 each, you can get a (short) tour of manhattan from above. Cheaper if you find a deal on groupon or livingsocial (I don't know how the rest of the country works, but those sites are the best way to find deals in NYC).
4) If not a helicopter tour, at least a double-decker bus tour. Or why not both? Even native new yorkers have fun seeing the city from a second floor view (because usually, new yorkers wouldn't be caught dead looking up).
5) Of course, you'll read about "top of the rock" and the empire state building observatory. Both are supposed to offer great views of the city, although I don't know anyway who's been.
6) Walk across the Brooklyn Bridge. One of the few free things to do in the city. Or, even better, bike across. I did this for the first time yesterday, and all I could think about is "how have I never done this before?"
7) I see you snowboard. Any interest in skating/longboarding the city? Maybe seeing some iconic skate/snowboard shops?
Sorry for the long reply, I could go on for days and days about this city though. These are my top picks though.