In Europe, sure, but not in the states. Passenger trains stop only at select few cities. More-than-likely, if you travel by train, you're going to have to drive or get a ride to the station, which is probably out of the way and in the middle of nowhere, then, your train will almost definitely make multiple stops, then when you finally get to your last stop, chances are, it's a long way from you final destination, so you're going to have to drive, get a ride, or take a bus eventually. Unless, of course, your final destination just happens to be a major hub. In the end, it'll be a few days before you get to where you want (the U.S. is farking big). It's just more conveniant to take a plane in the states, especially if you're traveling from one ocean to the other. Preferable? Not for me, I'll stick with my train which I have to drive to, and make those great stops in the heartland, then take a scenic bus trip to my intended destination. But meh, I like some good travel, especially if it's by train.
Also, even a bus station beats an airport, any day. Man, I remember being in a Turkish airport once, with a bunch of unibrowed security gangsters trying to cop a feel on my mom.