Funny thing most Americans don't know is that international coach is really decent too. E.g. I've never been on an intercontinental flight without unlimited free alcohol aside from on Delta, and any plane put together in the past few years will have USB/power sockets in every seat.
for someone who'd never flown anything other than coach, the experience was mindblowing, especially since the upgrade was only $50 at the airport.
i'd love to fly first or business again when i eventually go to europe, but as a hypothetical exercise i checked prices, and a firstclass roundtrip tickect is roughly $20k and business, though much better, is still $6k (i just checked lufthansa.com for sfo<->fra leaving august 4 and returning sep 1, so i'm sure better deals exist). If I flew coach, the whole vacation could be $6k.
i'm splurging and flying "premium coach" (or w/e the hell they call it on Virgin) on my next vacation; we'll see how it compares....