I've always wondered how it works for people who take Amtrak to/from the airport - actually, mostly from. To get to the airport, you can reserve in advance and take advantage of the saver fares, and it's not a big deal. But what happens if your flight is delayed by several hours, and you miss your reserved train from the airport back to home? I guess you could cancel online from the plane (assuming you have wifi), but then wouldn't you have to buy a new ticket at a far higher price? Or do the airport trains have a different pricing model?

When I lived in DC and had to take a flight to/from BWI, I'd take the bus to the Metro, and if my flight was very early or late, a Super Shuttle. But that was over a decade ago.