Dulles (IAD to you frequent flyers and pilots) has a phenomenally cool terminal. It opened in 1962 and sees over 27 million passengers a year. There is a ton of construction now as they are building a train system to the two satellite terminals.
My mom loves Dulles too. She especially likes the The Mobile Lounges. You can click the link for more info but here is a great paragraph about these tres moderne beasts, also part of Saarinen's design:
This was the first US airport designed for jets and so there was no precedent for Saarinen to follow. One of the most distinctive features of the airport was the lack of any building extensions onto the airfield for aircraft loading. Instead passengers traveled from the terminal to their planes, which could be waiting over a mile away, on strange vehicles called Mobile Lounges and Plane-Mates. Saarinen viewed these mobile lounges as an extension of the airport. They were mobile buildings that served as transportation. Apparently when the lounges were first introduced they had a bar onboard and it was possible to drink cocktails while being transported to your plane!
I enjoy flying into and out of places that are visually stunning and have some history I don't expect.