IMHO, the New York Grill is absolutely over-rated in terms of quality of their food. The view is one of the most awesome ones, though. So I suggest you might stop by the bar for a drink. But then if you are staying there, you might have the similar view from your room....
the New York Grill got most comments from Zagat survey in Tokyo. It does not mean it got the highest rating on food. At the price they charge, they should be alot better.
Few people do not use the basement shopping/restaurant floor, called Park Avenue, accessible with only one of the three elevators.. the one that goes down to the parking lot. At level B1, there is a wonderful Sushi Bar, Sushi Shun. and there is a high-end convenience shop to stock up to avoid their exorbitant room service charges if you are staying for several nights. Even a post office and a nice hair salon and a quick massage shop as well as full-service Kinokuniya book shop.
I think one of the best ways to enjoy the hotel is not to go out of the property much, since the facility; gym, pool, spa and rooms are just so superb. Its a waste if you are staying there and try to do lots of merry-go arounds of Tokyo, IMHO.