My drive originates in Toronto, and is heavily dependant on which route I take south...through Detroit or Buffalo. Taking I-75 out of Detroit is about 100kms longer, but it keeps you out of slowpoke PA (is it still 55 mph there?).
Being in the logistics industry, I long ago learned that truckers are, without a doubt, the best radar detectors and traffic advisories out there. Hop on, tell a joke about the drive south, and ask what the routes are like. Let the kids say thanks to everyone, and you will find they will continuously update you along the way. Just keep doing this as they fall out of range, and you'll acquire new friends. For most truckers, the ability to help a kid get to WDW faster makes it worthwhile. I can easily say that I've saved 1-3 hours because of them...
As for driving, we leave Toronto around 8pm, so that the kids will soon be asleep (now 7 and 2), we drive through the night, eating up the miles while they sleep. The next day we take more breaks, but it gets us to WDW in enough time to eat dinner, let them go crazy at a park and/or pool, crash...and then it's off to the parks. Of course, we crash with them by 9-10pm the night before (I normally fall asleep at 2am, so that's pretty early for me).