1. Zurich (ZRH)
I put Zurich first because it’s got something none of the others do: hiking trails.
The grounds surrounding the airport and nearby villages comprise a nature preserve. There are 12 miles of paths, wildlife like rabbits and wild boar, and even a park ranger force.
The best part is travelers can rent bikes ($20/4 hours) or inline skates in the airport (upper lever, near Garage 2), store their baggage while they go out for a pedal, and then shower up ($15) before their flight.
Check out this story for more.