St. Petersburg Yacht sales and Charters
Would recommend checking out St. Petersburg Yacht Charters. We do weekend trips all the time on our boat out of the St. Petersburg Municiple Marina. A weekend or 3-4 day trip could consist of hiking on Egmont key, anchoring at Desoto or Emerson Point, spending a night at one of the two great marinas up the Manatee river, and dinner at Moore's Stone Crab on Longboat Key There is a nice anchorage in Longboat key with a couple of nice spots for dinners.
The Manatee River has two great marinas with excellent restaurants (Regatta Point Marina and Twin Dolphin Marina.) Have stayed at both and rate both equally great. About a 5 hour sail from St. Petersburg depending on wind.
Moore's Stone Crab is a great place to stop in and have dinner and stay after a day anchored off Egmont and hiking. No cruiser facilities but they let you dock there overnight if you eat dinner there. It's about 9 feet at the dock MLW.
Mar Vista is next to Moore's but they don't have overnight dockage. The anchorage is very protected and most would rather anchor anyway.
If I had my pick I would charter out of Burnt Store in Charlotte Harbour though. It's only about a 2 hour drive from Tampa. Cabbage Key, Cayo Costa, and Boca Grande/Gasparilla Island would be my destinations.