My favorite beach on Sanibel is Bowman's Beach. The actual beach itself is a bit of a walk from the parking area, but there is no development on the beach at all - it's just you and nature. The shelling is fantastic, probably the best on the island. There's a huge, natural osprey nest in the parking area. Also pelicans and dolphin sightings on the beach regularly. It's beautiful.

On Captiva I like the beach just out back of the Mucky Duck restaurant. You can get a guiness and sit in adirondack chairs while a band plays outside the restaurant. As the sun goes down there is usually a crowd on the beach who applaud the performance the way they do in Key West.