Hey broobruce, Just an observation here. If you leave Lake City around noonish, that's going to put you in to Atlanta, Ga right around rush hour. Atlanta traffic is horrible pretty much all the time but during rush hour it is more Stop than go. You may want to adjust your timing to miss Atlanta Rush. Also, There is a 24 hour Walmart at exit 174 (off of I-24) in Chattanooga Tn. This is a great area to stop and fill you gas tank and get last minute supplies before making the final push to Bonnaroo.
Just remember too with ATL rush HOUR, it starts around 330, and runs til around 7. Depending on the weather too of course, because people in ATL forget how to drive if its raining...don't go around the city, 285 is worse than 75/85 straight through most of the time. Through trucks are not allowed to go through the city so 285 is a lot of trucks...the 15 mile stretch from 285 north through Cobb County/Marietta area will be the slowest/worst congestion of the whole ordeal. But smile, cause after that its free sailing!!