Here's an idea...how about starting your trip so you drive through Atlanta around 3-4am?
We live in West Central Indiana. From 'this neck of the woods', if we leave around 6-7pm, we hit Nashville at 11:30pm, Atlanta around 3-4am and arrive at WDW around 11am (and hopefully just in time to get an early check-in). What's nice about this plan is:
1) You have all day to make last minute preparations before departure.
2) The traffic has lightened greatly by 7pm.
3) Its dusk / dark / dawn (which may not be an option for some) for over half the trip, so no sun blinding to worry about.
4) If traveling with kids, they can watch a couple movies until 11-12 then (hopefully) 'zonk-out' until the next morning...giving you and your significant other some quiet time.
Of course there are disadvantages in traveling at night:
1) The traffic & cop ratio narrows, making you most susceptible to traffic stops (

I had no idea I was driving 85MPH officer. My speedometer is out of calibration and my wheels are oversized

)
2) More wild animal activity in early evening and early morning hours.
3) Your forward viewing range is lessened because it is dark.
4) Rest areas and pit stops that look 'safe' at day take on a totally different personality at night. What is 'safe' at day may not be approachable at night.
5) Fewer restaurants
6) Few (if any) open attractions along the way
I'm sure there are other pros and cons and my listing may ruffle some feathers.
So, heres my 'disclaimer'

The above listing of pros and cons only represent the opinions of this DIS member and may or may not reflect the opinion of fellow DIS members or
www.disboards.com 