You could also book Roscioli Salumeria con Cucina, try to get the wine cellar.
Most restaurants in Amalfi are within the city, but there are a few on the beach, some with beach amenities. The Marina Grande is right on the beach and it is quite good. If you go during the day the also have beach chairs that you can reserve and have lunch and drinks there. The pizza in Amalfi is also very good, same as Naples.