What about leaving later in the day, say as late at 9:30 to 10 am?? You miss most of the AM rush in Chicago and you fall after the evening rush in Atlanta. Granted, we've done this mainly on Saturday, so not so sure about Fri. The down side is that you get into Macon, south of ATL, around midnight or later, esp. with the time zone change, and you still have a pretty long drive the next day.
Also, we often drive through IL instead of IN to avoid the heavy traffic through Gary/South Chicago. It's a longer drive in miles, but less wear on the driver.