We live in Illinois, just south of the Wisconsin border. Milwaukee is 1 hour's drive north for us. So you're just an hour more to WDW than we are.
We've driven to Orlando 7 times now. Here's a conglomeration of our past drives.
We leave at 4:30am. This way you get around "the horn" of 80/94 south of Chicago at the Indiana border and get yourself southbound on I65 before all the traffic starts. You must avoid this. Must. If you leave at 4am, you will be fine. Probably at 4:30am you will still be okay. Any later and you'll hit traffic and stuck or going 25 in a 55 which will really slow down your whole trip.
We take the bypass around Indianapolis because you'll be hitting it around rush hours. It's very fast. Remember that the speed limit once you hit Indiana is 65 or 70 and then it's 70 through Kentucky, Tennessee, Georgia, and Florida. Cruise control at 78 and you make good time.
We've stopped at the Kentucky welcome center at the border and picked up coupons for the National Corvette Museum in Bowling Green. Also the Lost River Cave (boat tour through an underground river) in the Mammoth Cave area. Both of these are right around lunch time. You can stop for lunch and do a tour.
We've made it past Chattanooga (Expensive hotels for overnight and some pretty bad neighborhoods too. We stayed there once and there was barbed wire around the hotel grounds. We asked where to eat and the lady at the hotel said she wouldn't recommend going out, just order in pizza or something. Geez.) and usually stay just over the border into Georgia. There are many hotels at good prices before Atlanta with close by chain restaurants (Red Lobster, Outback, TGIF, Joe's Crabshack, Olive Garden, etc).
In Atlanta, we stopped at The World of Coca-Cola and it was pretty neat for the $15 adult admission price. They open at 9am and we stopped because the timing was right.
Be sure to stop at the Florida Welcome Center! It's been there for decades and they still give everyone a fresh orange juice (or grapefruit juice nowadays too!). You can also get brochures on Disney (individual maps of the parks and a "times guide" that can be very helpful to know before you get to WDW) and other places. Great reading for the kids in the car.
It's fun to see the palm trees for the first time and get a pic with the Welcome to Florida sign!
We usually get to WDW around 2 or 3 or 4 pm, even with these stops.
You can stay anywhere north of Orlando so that you can arrive on your first day at WDW in the morning and go to a park. But it can be done in just two days.
On the way back, we usually stopped in Tennessee or just into Kentucky.
The Great Smokey Mountains are really neat to driver through!
It's not a bad drive at all. Have fun!
