I bought a Calton Case (made in Canada) and I can't recommend it highly enough. These cases are tailored to fit different sizes - mine's a dreadnought - and the instrument is held in place tighter than a crab's ass in an undersea sandstorm, safe from damage. I always have checked my guitar, strings loosened, and I've never had an accident or lost one yet. Plus, arguing with airline personnel and security these days is liable to get you arrested. There have been other threads on this very topic, right after 9/11 if I remember correctly. Perhaps some kind 'Catter will provide the blue clicky.

Seamus