Having stayed at the Marriott Marquis quite a bit and now a commuting New Yorker, I always, always recommend it as a central place to stay. While in Times Square you get the feeling of being in the center of the world - all of New York City is around you and in the midst of it all you are in a glass portal that is home base. The value for such a location is perfect - theater, shopping, food, is all within a ten block radius of midtown, but a quick subway ride from the 42nd street station will get you all over Manhattan.
I deinitely agree. A group of business associates and I stayed at this hotel several years ago. My room had by far the best view of Times Square and one evening late we all just gathered there and took in the view while we enjoyed a few beers. NYC has much more to offer than that, of course, but it was time well spent!