Hi
We've driven 3 times from Milwaukee with our 4th time coming in July, so maybe I can help a bit
My first advice would be to get a triptix if you're a
AAA member.
Next, we've taken two different routes, one through Indiana and the other through Illinois. I like the Illinois route better, because you avoid more major cities. We do try to get thru Chicago very early (like 4 AM early

)
The routes:
Illinois route
I94 to
I294 to
I57 to
I24 to
I75 to
Florida Turnpike
Indiana Route (this is the one AAA will give you)
I94 to
I294 to
I80 to
I65 to
I24 to
I75 to
Florida Turnpike
We try to make it to somewhere in Georgia (past Atlanta if we're lucky) the first day so we don't have as long the second day.
It takes about 12 hours to reach Chattanoga from Milwaukee (south side) and going thru the mountains during some daylight hours is easier than at night.
We don't like to make reservations for our one night on the road because we never know how far we're going to make it; ie... we would hate to have gotten stuck in a traffic jam or two, or bad weather, then be hard pressed to make it to that hotel reservation.
We have a TV/VCR for the car, I try to tape stuff the girls haven't seen before or for a while so it holds their interest. They also bring their gameboys, cd players, and maybe a few other small games to play, coloring books, books to read, snacks and a cooler.
If I think of more I will add it later or if you have more ???s