The kids will sleep soundly after having fun in the sun at Plage de Capu Laurosu. Search for cute critters like crabs and snails, dip a toe in the water or throw a Frisbee around!
You're spoiled for sightseeing choice when in Propriano. Plage de Capu Laurosu is a good place to begin here, but there are lots of other interesting places to visit. Propriano Beach, Filitosa Corsican Prehistoric Site, and Portigliolo Beach are not far from the stretch of coastline and and will cap off your day nicely.