Rainbow, Captain Frenchy, Le Soleil, LoLos, Sunset, G's Snack, Enold's, Calmos all come to mind as being open for lunch daily (G's is closed Sundays) and I'm sure there are others. A number of the fancier restaurants will open for lunch if it is high season and/or if there are a lot of cruise ships in port. Some places open fairly for the brunch crowd - you won't have trouble finding a nice lunch meal in Grand Case.