To supplement jlo meins post:
Broadwaybox.com is way better thank TKTS. Better selection, get tickets days in advance rather than the day of a show, and avoid the lineups.
I'd go to Brasserie Les Halles (of Anthony Bourdain fame) over Peter Luger. Great french onion soup, and steak frites. And it's in Manhattan so it's convenient.
If you're into shopping go to the Woodbury outlets, most of the well known designers have outlets there (ie. D&G, Hugo, Chanel, Gucci, etc).
http://www.premiumoutlets.com/outlets/outlet.asp?id=7
What are you interested in doing while in NYC? Then it's easier to give advice and avoid the typical suggestions.