All the above are really good.
I would also recommend:
Gotham West Market – mixed street food market not far from Times Sq. youngish crowd, great food and not expensive.
Sandmans Tour – free* walking tour around the south of Manhattan. *you are expected to tip the guide
Katz Deli is brilliant but be prepared to queue and go hungry the sandwiches are massive.
If he is interested in social history the Tenement Museum gives a good insight into what life was life for the immigrant communities as they moved in to the city.
Try to get tickets for live sport. We went to the Yankees and it was a great Friday night out. We are planning to go back later this year, partly to watch more baseball.