Well, if one narrows down the options a bit, it becomes far more tractable. Considering that Google's flight search only works for domestic return trips of 15

Well, if one narrows down the options a bit, it becomes far more tractable. Considering that Google's flight search only works for domestic return trips of 15 days or less (it didn't seem to give me results for anything longer than that?) and doesn't allow stopovers or open jaws, it's entirely possible that the complexity is much reduced.