Start with a bus tour - check them out timing on the web. St. Patrick’s parade is in March. Take your wife to Broadway show at night or if she is busy, check out a game as Madison Square Garden. There is also the Statue of Liberty and Ellis Island. WTC, UN, Empire State top, Fifth ave stores. Fugetaboudit - you won’t have enough time. Grab what you can.
I am actually going on March 16th through the 20th.