If your tour starts in Sorrento, wether you are staying in town or visiting for the day with a cruise ship or a private boat, you may want to spend a day exploring the Amalfi coast. I would pick you up wherever you want to be met, and from there we would start your private tour. We would leave the bay of Naples and approach Positano in less than an hour (time depends on pick up location), allowing time and stops on the scenic road to take pictures and appreciate the breathtaking views. You could then continue with an optional stop by the Grotta dello Smeraldo (Emerald Grotto), and then on to the town of Amalfi to see the Duomo of St Andrea or explore the narrow streets of the old town. Leaving Amalfi we would drive up to 1000 feet to see the town of Ravello and optionally step inside its villas. Villa Rufolo and Villa Cimbrone are Ravello landmarks. Lunch could be here in Ravello or some other nearby scenic location, and then from Ravello I could drive you back either via the same coastal road, or over the mountains and by Castellammare.