I've been known to hit up the Five Guys at DCA and LGA for breakfast before a 7am flight. Something about it still hits the spot that early in the morning.

I agree that it's not the "best" burger in the world, but for a fast food burger it's definitely up there. The variety of toppings and generous portions of fries are a big plus, as are the made-on-the-spot burgers compared to the heatlamp, premade kind you get at McDonalds or BK.