Patricia,
Auto-Train is a wonderful way to travel. The coach seats are comfortable, and yes, it is most certainly worth it. I always consider the train trip to be an enjoyable part of the vacation - not just a way to get to the vacation. You save 900 miles of driving, and avoid having to spend the night in a motel along the way (thus you save that cost, and meals are included in the price of your ticket - this helps reduce the true price). I returned from WDW on this train back in July, so if you have any questions please ask. You may want to check the website listed below for Amtrak travel hints & tips.
http://communities.prodigy.net/trains/amthints.htm
The Amtrak website was working this evening, but it has seen a deluge of new passengers in the past few weeks, so it is sometimes S-L-O-W. Try to "play" with the dates and accomodations on the fare finder to get a better rate (always use the 30% sale). You might try accessing
http://www.amtrak.com after midnight. If you want to save even more, try to make the trip in an automobile instead of a Cherokee or Minivan. These are considered oversize vehicles, and cost on the order of $300 extra.
The car will be quiet enough to sleep comfortably (though not as well as a sleeper). There are occasional noises as the train passes over a bridge, as the wheels interact with a turnout, etc., but nothing severe (and you get used to them).
Also, call Amtrak and have them send you two things: the Amtrak 2001 travel planner and a copy of the national timetable (train schedules). This will answer a ton of questions you might not think to ask until you get on board! It also will help you decide if you want to take Auto-Train, which, again, I highly recommend.