I would love to be able to take the Gold Line to Ontario and fly from there. I haven't flown from there in ages, but it's much easier to get to in the morning from the SGV than LAX is-- it's the anti-commute direction and doesn't have the joy of getting through DTLA. And the metro has done a really spectacular job of making it painful to take the metro to LAX at all, let alone from the SGV The Flyaway bus from Union station mitigates that a lot, but is still subject to traffic delays, particularly near the airport entrance (they can take any route they want in between since they don't make any stops between Union Station and LAX).