We are 2 adults and 2 boys driving from Chicago. We are leaving Thursday 8/10 around 5:30pm we will venture through Indianpolis, Louisville, KY, Nashville, Chattanooga, Atlanta etc. We are planning on driving straight through with the exception of gas and potty breaks. I'm planning on driving the 1st part as I have horrible motion sickness and cannot truely sleep in a moving vehicle. Hopefully I can get us 9-10 hours down the road; then hubby will drive the last leg and I can doze or play games with our grandsons. GPS says 17 hours without stops so I'm guessing about 20 hours one way
I suggest you do not drive through Atlanta before 9 AM or after 3 PM. If you do, you're likely to lose a good hour or more in traffic. After driving as much as you'll be driving, that is definitely not what you want to go through. Atlanta traffic is horrendous (having lived in various places in the US, I can say this is one of the worst I have ever experienced). Accidents are a daily thing, people drive like self-entitled you-know-whats and rush hour makes living hell out of everyone. In fact, people choose where to live based on where they work in the city, because a 12 mile commute could be 30 minutes or could be an hour and a half. Avoid rush AM or PM hour and you should be fine.
Also, in case you are not familiar with the FL Turnpike, you'll need quarters. I forget how much I spent each way, but it was something like $3.00 or so (two toll booths). The toll booths may be manned or may not, and if they're not you'll be fined if you drive through without paying. FL does not make life easy for the tourist. Make sure to bring plenty of quarters and you'll be just fine.
Above all, have an amazing time!!!!