Good job on the Wicked tickets, it is one of my favorite shows.

Ground Zero is just a construction site at this point. However, I would suggest dropping by St. Paul's Chapel which is across the street from the WTC. Besides being a cool, old church in its own right, it was also used as a command center during everything. They have a lot of memorabilia inside that you can take a look at.

I don't know of any tours of the financial district and you won't be able to get into the NYSE because of security.

I took the double decker bus tour the very first time I went to NYC. It was good because it allowed me to get my bearings and hear and see some cool stuff. However, I haven't been on it since. I walk and take the subway so I can see more up close. I have never taken a carriage ride around Central Park but I would imagine if you want to see it quickly, that would be the way to go. I have walked it several times and that is the way I enjoy it the most. Be sure to see the Bethesda Foundation and Bow Bridge.