This is not going to be easy since just about every city uses a different system. You need to look up all of the systems along your route and program them into your scanner. You are covering a very large area.
As was mentioned, you would need to have a ton of frequencies loaded, but I have made the trip from Cape Canaveral up 95 and across I10 to I75 and north past Macon and Atlanta towards Chattanooga direction a number of times.. (I actually bear off onto I575 north of Atlanta)
On the last trip, I used my BCD996T with GPS control, and programmed a number of cities/towns on the route, but found it more trouble than worth..
In FL, of course, FHP is encrypted, so that's unusable, but I narrowed it down to a few standard VHF frequencies for SOME listening pleasure. Like 155.16, 155.34, 154.905, 155.37, 154.680, 155.445, and some of the other historically active frequencies for fire/PD/med and intercity, etc.**
While IN GA use 154.680 and 154.800 for GSP activity - pretty active statewide.. as is 155.34
Also 146.52, 146.55, 146.58 for occasional traveling "Ham" conversations en route..
Chattanooga and up to Chicago, I can't help with, but many of those frequencies above should still give some activity.
** Probably best to look though the Listings here on RR for the areas you will pass through and use some of the more generic ones..
Not a LOT of info, but may give you some stuff to listen to..