Take a look at a couple of articles Doug did for his survival kit posts concerning vests:.
http://www.equipped.org/onyourown.htm
http://www.equipped.org/avvests.htm
You might want to consider a manually activated pneumatic PFD as offered by SOSpenders, Stearns and Mustang. There are even vests which store in a waist belt pouch for quick donning. The pneumatics would be cooler to wear (important in Florida) and one or more survival kit pouches can be attached to the rear of the belt. In our north country and Canadian canoe trips, vests are kept handy, but generally not worn except in swift water, wind or when paddling solo.