I have to disagree respectfully with Catman's favourable opinion of the Plaza. I was quite disappointed and now stay at the Waldorf exclusively.
I had a long business trip to NYC in December and therefore brought along my fiancée. We were sent to a room where the door would not open. After calling reception and waiting for 15 minutes, a bellman took us to another room. This on had no heating. Next, he took us (remember we are dragging along our luggage) to a tiny decrepit old room with no operating TV or bathtub. The FOURTH room had some other problem that I have blissfully forgotten.
Finally, after a complaint to the manager we were upgraded to a nice suite. All seemed to be well.
That Sunday we asked the Plaza concierge for a brunch recommendation. He highly recommended Tavern on the Green and made reservations for us. He said we had to be sure to dress very nicely, as it was quite formal. So we don our finery and proceed to the WORST DINING EXPERIENCE EVER. After waiting forty five minutes (what kind of pull does this demonstrate for the Plaza concierge?) among t-shirt clad tourists (so much for formal!) we were taken to a table and served a truly inedible appetizer. This was the only time in my life I have simply left a restaurant. This would not be the fault of the Plaza had the Concierge not recommended it as one of the finer dining experiences available.
End of rant.