Because of our schedules, about the only time my wife & I can usually go to WDW is during hurricane season. And because my wife is a teacher with a pretty hard-core work ethic, she doesn't want to miss the first day of school for anything, even an act of God. We drive to have the option of delaying our trip, or leaving early if a hurricane blows through, closing the airports or causing road damage that would make going home problematic.
As far as the OP goes, I can understand thinking about taking a train in your position - going alone, no one to share driving duties, wanting to arrive rested and all that. I'd say, though, that if the trip starts to suck, it's almost impossible to make a bad train trip better, but a bad car trip, OTOH, you can always pull over, take a nap or get a hotel over night, have a leisurely non-cramped meal, go to a local mall, take in a movie (also a good place to take a nap, imo), sightsee, etc. I'd also suggest, if you have a car with satellite radio and/or multiple CD changer and/or an ipod hookup, you can have so much entertainment at your disposal, the drive is hardly a chore. When I drive down, I practically OD on Howard Stern/talk radio, standup comedy, old time radio like Jack Benny & Suspense, audiobooks...sometimes my wife will watch TV shows or movies I ripped to my mp3 player while I follow along listening to the piped-in audio. One trip, while she slept, E! Entertainment Raido had the audio version of the E True Hollywood Story of the making of Jaws, which was a blast to listen to. And Sirius has plenty of traffic/weather channels, and that helps anticipate traffic jams and we either pull over and wait it out or find our own detours.
I'd say, unless there were things you had to get done on a laptop while traveling, you'd have a greater chance of enjoying yourself driving. The main other exception is if some Hawaiian Tropic bikini contestants were on the same train as you, and while anything is possible, I wouldn't count on it.