There are endless discussions on this board about what is the best steak-house. The fight usually comes down to Peter Luger's in Brooklyn or Keen's in Manhattan They are both fantastic, but since you want Manhattan, Keen's it is. Do yourself a favor and get the porterhouse (and/or) a Mutton chop. I like to sit in the Tap room (near the bar) by the fire - though there are no reservations taken there.
72 West 36th St., New York, NY 10018