Sounds like you've made your mind up Flex, good for you.
I live minutes off I75 at went to FLA many times and also have traveled up your more that that.
There are zero tolls down 75 all the way to Sarasota from Detroit. The only toll is the bridge to cross the border, just came through there a few months back and since the have the construction work done it's a lot nicer/easier to get on I75 south than it was in the past.
As far as the drive, coming through MI and Ohio for the most part is the same as driving from Toronto to Windsor. Once you cross the Ohio River is does get more scenic in Kentucky, Tennessee and north Georgia. Ohiofisherman is right about the rest of Georgia though.
jjcanoe's first post about leaving 75 heading east over to NC is spot on, very scenic, and that avoids the trouble spot on 75
As far as speeding, keeping it at under 10mph over the speed limit will generally keep you out of any trouble down here as long as your not weaving through traffic. Wear your seat belt! They will ticket you in a heart beat for noncompliance on that.
Have a safe trip an enjoy yourself.