Location, location, location
Location is the best reason to stay at the Marriott Marquis: It's right in the heart of Broadway. In fact, it's right next to TKTS, where you go to buy same-day half-price show tickets. Our room on the 22nd floor was totally quiet, nonetheless, and we had a fairly impressive view of Broadway signage. The curtains were able to block the light out entirely while we slept, though.
The most annoying thing about the hotel, though, IMO, is the elevator system; instead of pushing your floor button inside the elevator, you have to "program" in the floor outside the elevator when you are calling it. The elevator then goes only to the floors that have been programmed in. BTW, the concierge is on the 8th floor, and the elevators have glass walls--for those with squeamish stomaches.