Given 65 is rougher than 75. I still prefer 65 as I think the traffic is lighter. it's not as hilly and I don't have as much downshifting. From my house to Chattanooga there's only about 10 miles difference.
Indy is getting ready to redo the exit from 465 to 65 on the south side. I can take state hwys and avoid Indy.
Louisville is going to be building a new bridge, making one for north bound and using the old one for south bound traffic. They are also talking about making it a toll bridge, taking a pic of your plate and mailing you a bill for the fare.
Nashville has options if your going down I-24. Briley Parkway but I don't like the 4 stoplights. I have been know to use exit 2 in KY going through Portland to Gallitin and then down to 840. Seems to take the same time in the car but can be a hassel with trailer. Going on toward Alabama your best just following I-65 markers but there are several times you need to watch which lane your in for the road divisions.
Going north give me I-69 all the way up and avoid Detroit like the plague with a switch. This is my preferred route to Toronto, 8 hrs.