A good case with "fragile" stickers on it. If you're travelling between first-world countries like Britain and the US, you're probably OK. If you're travelling to a third-world country like Greece or Turkey or worse, only take a guitar you can afford to lose, because the baggage handlers really don't care. But things can still get busted whatever happens - think Tom Paxton's "Thank you Republic Airlines" - so get it insured.

Graham.