We have taken the autotrain from Lorton, VA to Sanford, FL twice and are doing so again next year. We'll never fly to FL again. We love it for so many reasons. The price has always been cheaper than flying (we're a family of four) when you consider the cost of tickets, parking at the airport, checked bags and a rental car (I love having my own car at WDW, not a fan of WDW transportation at all). Plus the convenience of being able to pack whatever we want without worrying about weight and/or cost and not having to arrive at the airport two hours early to get through security, no worries of delayed or cancelled flights.
We always get two sleeper cars right across the hall from each other. We pack whatever we want into our car, which usually includes bottled water and lots of snacks for the parks, and drive to the train station, check-in and we're officially on vacation. The dinner they serve has always been good (and includes wine). After dinner we hang out in our rooms, the kids watch a movie, DH and I read and relax. The porter comes by to make up the beds when you're ready. In the morning we grab breakfast and get ready to get off the train. We've always gotten to FL by 9:30 am and had our car by 11:00. Sanford is a 30 minute drive from WDW. Like I said I'd nver fly to FL again with the autotrain being available. It's a much more relaxing way to travel. Yes, you do need to add two days to your trip for travel, but fortunately that's not a problem for us.