For our day trip on the Alafia River (pronounced by locals: Al-a-fy), my sister and I put in at Alderson's Ford Park near Brandon, Florida. Take-out was about 11.5 miles downstream, at Alafia Canoe Rentals, and they were kind enough to shuttle us back to our truck for about $5.
This is a smallish river with not much descent, but the current is deceptively fast. Because of the many sharp turns, and the debris that accumulates in each turn, the current could sweep you right into a strainer, deadfall, or cypress tree before you know it! Only a few small shoals near the take-out--the primary challenge was figuring out 1) where the gaps in the debris were that you could shoot through, and 2) how to aim the kayak while paddling like made to counteract the current sweeping you sideways!
In two spots, a tree trunk crossed the entire stream: one just below the surface of the water (my sister got stuck), and one about two feet above the water (fun trying to play limbo in a kayak without dumping over).
The scenery is very "Old Florida"--huge cathedrals of cypress trees (and cypress knees poking up out of the water like gnomes), sweeping Spanish moss, alligator lilies, ferns--very green. The river is a protected area, so for most of the trip, we saw no development on either side. Several times, we achieved that blessed moment when you could hear *no motors of any kind* at all. Bliss!
Paddling time--because you had to paddle hard most of the trip in order to navigate--was about 3 hours. The family that runs Alafia Canoe Rentals was very hospitable and shared some good stories!
$5 for shuttle.