As a big fan of air travel, I'd like to figure out which airports a keen traveller should consider putting on their bucket list - considering the airports as a destination in themselves, or at least a noteworthy place to travel through - rather than simply a way of getting from A to B. I would nominate as a starting point:
London Heathrow (Terminal 5) - a lovely, modern, airy airport terminal - huge and impressive. Perhaps not the friendliest or always most efficient of destinations, but nevertheless outshines many western airports.
Vancouver - like being in a jungle-themed mall or theme park, fun, airy, and pleasant.
I'm thinking primarily here about the architectural or artistic merits aspects of the building or complex itself, not so much about customer service or other such aspects, in an attempt to keep this question focused. I'm not looking necessarily for personal opinions, more airports where there's always a good documented consensus that they are noteworthy.