I just finished my lessons with Boca Ciega Yacht Club in Gulfport. (St Pete area) I can't say enough good things about the people at BCYC.
Classes are offered twice a year, April and September.
BCYC Sailing School St Petersburg, Gulfport, Florida
I am not affiliated with the school in any way, just a happy customer. The courses are taught on Catalina Capri 16.5s Classes are on Wednesday nights with practical application (sailing) on Saturdays or Sundays (you pick) over a 5 week period. Classes fill up quick, so if you are interested then I suggest contacting them asap.