Destination Wedding Gown

Hi - I`m getting married in Maui. It`s right by the beach and it will be an outside wedding and reception. It will be elegant but casual - my groom will be wearing khaki`s and a white shirt. Can anyone recommend a good dress designer...elegant but informal for a wedding like this?! I don`t want to melt in the heat but I want something pretty and flowing. Thanks for any suggestions!