Essential New York

I used this book (an older edition) on my first trip to New York City and I found it very succinct and helpful. If you don't want lengthy descriptions and lots of historical background, this the book for you. It gets to the point about some of the "must sees" and "shouldn't miss", as well as warning you about some cultural differences. The Essential series is also great because it's thin and lightweight, yet some color pictures so that you can recognize some of the sites you're searching the skyline for.