I prefer the Amex sky guide. It is laid out backwards from the OAG. In the OAG you look for the city you want to fly to and then it gives you flights there from many US cities. The sky guide, is set up listing the departure city and listing where you can fly to. I primarliy use it when a flight is cancilled or delayed (or if i'm delayed). It is useful while standing in the line to rebook to check you options. "okay I see Delta has a flight leaving in 45minutes, maybe I can get rebooked on that one..etc."
That kind of thing.