My cutoff used to be about 12 hours. Anything over that I'd fly. Nowadays, that number is about 4-5 hours tops. Most of the time, when you factor in wear on your vehicle, fuel, parking, tolls, rental cars, etc, let alone the time and hassle, the difference between driving and flying costs aren't so bad, depending on where you are going. I suppose it would be worse if you are trying to transport a larger family. With 2 of us, I'll fly when possible. I also don't believe I'm a big "convenience person". I'd rather not sink thousands of dollars to prevent minor inconveniences, but I am done with driving.