For travel of 5 hours and less, I'd disagree. The airport is a less efficient use of one's time, even if it is cheaper per mile flown. Traveling from SFO to LA

For travel of 5 hours and less, I'd disagree. The airport is a less efficient use of one's time, even if it is cheaper per mile flown. Traveling from SFO to LAX on high speed rail is far preferable to me than driving for 5 hours or a 5-hour airport experience. Mythbuster's recently tested this, and the actual difference between driving and flying door-to-door was like 15 minutes. A 2.5 hr train ride would not only be faster, it would be far more pleasant in terms of getting on/off, and in terms of comfort and space onboard.