I use trains for most of my long distance travel. Most of the time I don't need a car on the other end. When I do, either I ride with a friend I'm visiting or just rent one for a day or two. A lot of the time I'm visiting places with decent transit, SF bay area, Chicago, DC, NYC, etc. If I'm in a hurry for some reason, I'll resort to a plane, usually in just one direction.
Now on the coasts, from what I can tell, the train system is essential (Boston / DC corridor for example). I don't think there is a way for the air system to handle the extra traffic and who wants to deal with airports if they don't have to? Especially in the corridor, it's a stress free way to get from on place to another. You don't have to deal with road rage, or airports, or getting to and from the airport, etc.
Chicago is a great example of a city that would be totally gridlocked (way worse that it is now) without the extensive local and long distance rail system it has.
I don't drive a lot any more if I can help it. Though I did do one this spring, in general I burned out on long distance driving trips some years ago.