Haven't spent the day there on the beach myself, but many people recommend Love Hotel and Enold's. Staying at Esplanade, it's a bit of a walk to the beach if they're hauling a lot of stuff. I think, although I am not certain, that they have use of the beach at Le Petit, since they are sister resorts. If so, and if there is space, they could park at LePetit and use it as their base for the day, but there should be parking pretty much anywhere in Grand Case during the day anyway.

My favorites for restaurants right now are Ocean 82 and Bistrot Cariabes.