I need help with centerpieces for my destination wedding~?

We are going to key west to have out wedding. Usually traditonal weddings, one person takes home the centerpiece. Obviously with everyone flying in I doubt they would want the floral centerpiece. The wedding will be held outdoors, so it will be hot! I wanted some suggestions on different beach themed centerpieces, one idea I was thinking about was having a bowl with water and seashells and having floating candles and flowers, anyone have any other suggestions. Something simple but unique!