We do this drive from Cincinnati to Orlando every year. We have been doing this from the time my son was about 4 years old until now, which he is 10. I have a couple pieces of advice.
#1, put some extra pillows, blankets, etc. under the feet of your children (especially if they are in car seats). We don't realize how awful it is to have your legs just dangling there for so long and not being able to take the pinch points off where their legs go over the plastic part of the seat.
#2, I-75 is as close to the Autobahn as you will find in our neck of the woods. The speed limit most of the way is 70 MPH. I usually set my cruise at 77-78 and just go. I have to stay in the slow speed lane most of the time as you will get blown by at this speed.
#3. Travel time seems to be like this for us. We live on the East side of town, so it takes us 30-45 minutes to get to the I-275/I71/I75 interchange in Kentucky
Tennessee Border = 3 hours
Knoxville = 4 hours 15 minutes
Chattanooga = 5 hours 30 minutes
Other side of Atlanta = 7 1/2 to 8 hours.
Total driving time from our house to WDW property is usually about 13 1/2 hours of driving. Factor in any of your stops to figure out how far you can comfortably get.
We try our best to get to Tifton, Georgia each year on the first day. I have driven it straight through a number of times and this year drove it straight through on the way back. It is doable, by it is a long drive.
Tifton, Georgia is about a 4 hour drive in the next day. This seems to be just about right for us. It seems to be a nice distance to drive and if we get up in the morning at a reasonable time (say 9 o'clock), we can eat breakfast and get on the road by 10:30 or so. This gets us into our resort right around 2 - 2:30 in the afternoon. That leaves us a lot of daytime to still "play", plus our room is usually ready for us to check in and unload when we get there.
This year we stayed at the Country Inn Suites in Tifton. It was VERY clean, and quiet. You can pick up coupon books at any of the Georgia rest areas, or at just about ANY gas stations in Georgia that will cut your hotel costs down a BUNCH.
The Georgia rest area closes VERY early and the rest rooms are locked and not accessible after hours. I think it closes around 6 pm. So, plan accordingly for pit stops.
We usually try to leave so that we are through Knoxville by around 3:30-4 pm and thus we miss that traffic. That then has us hit Atlanta after rush hour. For Atlanta, we get in the HOV (car pool) lane and just glide through, it makes the navigation very easy.
On the way back, we make a 2 day trip out of it. We usually leave WDW around 1-2 pm and then drive to a town called Cartersville. This is about 30-40 minutes north of Atlanta. That leaves us a bout a 5-6 hour drive home on day two. We can then get home at a reasonable time and rest up for work the next day.
The Holiday Inn at Cartersville is very nice and has a nice hot breakfast in the morning. It is also a very low point option if you have reward points that you can use with Holiday Inn.
Enjoy your trip. I am sure you will.
Dizneykev
