Personally I'd be most tempted to bring the 18-270, assuming you can only be bringing one lens on body. I'd be thinking of the ability to be ready for most any shot opportunity, from wide landscape vistas to closeups of something very cool from a new perspective. The 17-50 is a fine lens, but what happens if you see something farther away that looks extremely cool, and the pilot can't fly closer? The 18-270 may not be as great as the other lenses in a direct comparison at a particular focal length, but it has the jack-of-all-trades versatility to cover all your bases.
As for settings, I'd imagine you'll be in good daylight - so low ISO should be fine. I'd probably stick with middling apertures - you don't need to worry about DOF, and won't need wide open, but you want good detail without diffraction losses. Remember that you might get some atmospheric issues - haze, cloud, smog, fog, etc that could fade your colors or lose details. Post processing to restore contrast should help quite a bit, but I'd probably consider dialing in a little underexposure, like -.3 or .7 to help keep a little more depth in the shadows and control whites and highlights which will blow out more easily in haze.