There is something to be said about the radical change that highway 90 in northern Florida takes at the town on Milton in NW Florida. Across the top of the state 90 is really great for cycling, except when you go through Tallahassee which has far too much dense traffic to deal with on a road whose paved shoulders have suddenly disappeared for a long stretch. Generally speaking though, 90 might be considered something of a cyclist's dream road.
There is plenty of room, and its shoulders are extensive and wide and run a very long way. Traffic is quite moderate. Its surface is smooth--until you get to Milton. Here is a verbatim entry from one of my less detailed journals.
"I just kept on pedaling through the small towns, through road construction, on an old concrete slab and brick road built in 1921, resting at small stores and grinding over the hills. The wind came from the side much of the time. From Milton, Florida and west, 90 turned bad for cycling with grass debris all over the shoulder, disappearing shoulders, and large expansion cracks, and a rough surface---very different from the rest of 90 across N. Florida."
April 30, 2007.