I've just come back, less than a week ago after spending 4 days in New York! I also went about 16 months ago. My itinerary was something like:
Day 1 (the day I arrived)- Macys and Times Square
Day 2 Staten Island Ferry, (this time I walked over the Brooklyn Bridge) Wall Street, Ground Zero, helicopter flight, Greenwich Village, Little Italy, Chinatown
Day 3 - Empire State, Fifth Avenue, Grand Central Station (one of my favourite buildings!), the lobby of the Chrysler Building, Rockefeller Centre (including Top of the Rock)
Day 4 - Central Park and the Metropolitan Museum of Art (this time I went to the Museum of Natural History)
Day 5 - Sunday brunch at The View - a revolving restaurant in Times Square then last minute shopping in Times Square before going to the airport.
I would highly recommend the guide book 'A Brits Guide to New York' - tells you practically everything you should need to know.
Have a wonderful time - though I'm confident that you will!