Just for back from NYC last week for the first time and loved it
I went to the following tourist attractions
MoMa, top of the rock, Empire State Building, circle line cruise and the American Museum of Natural History. We got the city pass its 106 for an adult..
http://www.citypass.com/new-york.
If you are going to the WTC Memorial you should reserve tickets in advanced and its free you can even reserve tickets the day of..few blocks around there is "Century 21" which is a crazy outlet that you can spend a few hours in, but a gongshow.
We got around by subway which is quite easy if you download hop stop..or google maps it tells you exact directions on which trains to take/transfer
I wish SNL and TV series were in season it be neat to see
Remember to bring comfy shoes for walking !