I suggest the Vinoy (Renn. in St. Pete) or Marriott Waterfront (Tampa).
Neither are on the beach, but are both on the water. Ren. Vinoy is a block from the St. Pete Pier.
Both are world class locations. I am partial to the Vinoy because of its rich history as an old historic hotel. (I live blocks away, but when they run dirt cheap rates, my wife and I stay).
Believe that is the only two in this area.