Best US airport:

San Diego: Terminal 2 is a delight to walk around because of the airiness and architecture. One of the few airports designed with people in mind. Oh and they sell Sees Candies. ^

DTW: MCNamara terminal only. I like the food concessions there, it's clean, comfortable and spacious. I've also never had to wait long to get from check in to the gate, so expdiency is also a bonus. Oh and they sell Sees Candies. ^

Worst:

MIA: Quite simply one of, if not the worst airport in the Western hemisphere. The place is crowded, dirty, smelly, poorly maintained, hard to navigated, lacking in decent food concessions, employs surly staff and is a hell hole on a par with hell.