Some things I will miss about America:
Appalachia: music, people, landscape
American libertarianism: not an entirely lost cause
Thanksgiving: America's best, most civilised, holiday
Amtrak sleeping cars and trans-America travel in general (except by air)
The classic American diner - especially in small towns where the waitress will always call you "Hon".
Skipping work for afternoon baseball (even in RFK!)
Commercials for "not available in stores" products such as "Miracle Putty" or "Magic Bag" or anything else that will change your life forever.
The American West: idea and landscape alike
Confirmation hearings (theory)
Proper country music: Cash, Jennings, Haggard et al. Also Graham Parsons and Emmylou Harris.
College football Saturdays in the fall (Go Blue!)
Cheap consumer durables. (Thanks China).
The Kirov Opera's annual visit to Washington.
But above all I'll miss the Idea of America: an idea that, however scuffed, endures and retains it's extraordinary power: an idea that every man is endowed with the right to pursue his own idea of happiness (every woman too, of course) provided that quest does not impinge upon the rights of others. That remains a revolutionary concept worth defending against enemies domestic and foreign. So too the notion that, with hard work and a dollop of luck, we may make some headway in the struggle to be true to the better parts of our better selves.
And some things I won't miss:
To Catch a Predator
The United States Congress
Immigration at JFK
Factory farming of livestock
People who bore on about Europe's future under Sharia Law
Confirmation hearings (practice)