According to some documentation I found at Parallax, some XBees have a range of up to 2 miles. It would be for an airplane (and possibly later for a quadrotor). My youth pastor's R/C controller has a range of just over a mile, so if that documentation is correct, range shouldn't be an issue.
I'm going for something like a Due for the ground station and a Pro Mini for onboard control. Based on what you are telling me, my idea is certainly possible. Thanks for your response, and kudos on your robot. That's a very cool project.