The kids will sleep soundly after a day spent at Su Pallosu. Look for crabs and other little critters, stick a toe in the water or maybe even fly a kite!
You're spoiled for sightseeing choice in Capo Mannu. Su Pallosu is a good place to kick off here, but there are numerous other interesting places to appreciate. Mari Ermi Beach, Putzu Idu Beach, and Is Arenas Beach are near the stretch of coastline and will fill in your day nicely.