I am on airplanes weekly and wanted a decent, indestructible guitar I would never have to check, and would enjoy playing. I tried tons of different options and settled on the Traveler Guitar MK-II. http://www.travelerguitar.com/. I play jazz, fingerpick, and folk. The guitar is good enough to practice with, and uses headphones. It also is good enough when I take lessons away from home. Of course, I miss my Bourgeois, my Collings, and my PRS, but there is no way I am going travel with them. This works and works well. I paid $450. Good luck.
Lots of people really like the Composite Acoustic (CA) Cargo, for travel and other purposes. Price is likely to be well over $500, however. Still, this little guitar has great tone, is easy to play, and can take on extreme conditions that other guitars would cringe at. http://www.compositeacoustics.com/Files/Product/Cargo_277/The_Cargo_90.asp
I've got one of the original Pro Series Traveler guitars with the detachable lap rest, and I don't recommend it because it's hard to position comfortably, even with a strap. The MK-IIs look like they'd be much more playable shape.