OK, now that I've got my head firmly released from my arse (thanks RFH), let me offer some more. Seems to me your biggest obstacle is time. I can (now that I'm sober) suggest a bunch of detours, but they will take time. None the less...:
1. You could take a right at Margerum Alabama and pick up a section of the Natchez Trace. That piece running in the direction of Tupelo is very little-traveled. Not too many landmarks, but it's nice. You can also plan a stop at the natural bridge - that is kind of cool and out of place for Alabama. Then run Hwy 278 through the Bankhead N/F - that road is very nice and pretty quick as you run through the forest. Then meet your route back to Cullman. Something like this:
https://goo.gl/maps/quUcb3SC2bv
2. After Daytona, get back to Gainsville, and then get to Hwy 98 and stick with it. That is a beautiful ride and is the quintessential Florida that I like. The one that doesn't include Mickey Mouse, Condos, or any other tourist trap. There are so many awesome places to run down to the coast and wander a little, but my favorites along this route are: Manatee Springs State Park, Tide Swamp Wildlife Mgmt Area, St. Marks Wildlife Refuge, Alligator Point, and St. Joseph Preserve (Port St. Joe). This would an awesome ride.....
https://goo.gl/maps/wAAqoF8FvUQ2
3. At Panama City, get away from the coast. From there west, it's really getting touristy and crowded and the traffic (even in October if the weather is good) is going to be a real PITA. Hwy 20 is a great alternative to I-10 and goes through some foresty swamp. You can then pickup the slab or even ride Hwy 90 to Mobile - the bridge across Mobile Bay is kind of neat. If the traffic is bad leading up to the bay on the slab, take Hwy 90 and avoid the tunnel.
https://goo.gl/maps/EnrqUHavhY52
4. On the other hand, avoid Hwy 90 going through coastal Mississippi. It runs about 25 mph and the casino crowd just pisses me off. Picture 75 year olds that are half-blind and should be driving anything, much less a 6000 pound Cadillac. Hop on the slab and make some time. Like this:
https://goo.gl/maps/vPvLohucGFp
5. I suppose you must go to New Orleans, but quite frankly I'd avoid it. You could cut that triangle from Mobile and ride through some nice stuff heading northeast. I know I'm wasting my keyboard, but I thought I'd throw that out.
Hope this helps.