I wont be in ATL
but we got stuck in two hours of traffic on the way to Dallas making the drive just under 14 hours (and I go on family summer vacations almost every year). I have plenty of experience
Some of our team on the way to Dallas got the "TWSS" Color Game started. Nothing like 14 hours of shouting "magenta". And I know this will sound terrible, but homework. I did all of mine on that bus. It a great time for reading too if people let you lol. Do trivia over each other to see how close you've all come as a team. Play games like "Big Booty" and "The King of France has lost his Pants". And I've always wanted to do this one, but i don't think many people would go for it. Have everyone be their favorite fictional character the entire trip.
My suggested movies are Fast and Furious, Accepted (one of our mentors brought it and had us watch it), Star Wars (preferably the original trilogy), Indiana Jones, Back to the Future I, II, and III, anything Harry Potter, anything Disney-Pixar, Transformers I and II, The Haunting in Connecticut, Robin Hood: Men in Tights, Wayne's World I and II, Speed Racer, any Sing-a-Long and Get Smart.