I am not in Florida, but I really like the Double Barrel VP's. I use them in conjunction with "fly mineral", and pour on. They are usually effective for about 2 months for face flys.
I am sensitive to organophosphates, so they make me "sick" for a day or so be careful and wear latex gloves and long sleeves.
Bayer tags are also pretty good, but they seem heavy for small calves.