I recommend Montetti Taxi service to see the Amalfi coast and Paestum (Greek ruins).
We visited Italy in March, and had only 1 day to see the Amalfi Coast and Paestum. Raffaele tailored our visit exactly as we wanted him to. He picked us up at the train in Naples (we came from Rome) and took us down the coast, over to Paestum, and back to Naples for the night train back.
He knew exactly where we should stop and take photos--and he could work my new camera better than I could! It was a fabulous day and we were thrilled. He was professional and helpful, while allowing us time to wander by ourselves.
I found him in Rick Steves' Italy book. His website is http://www.monettitaxi17.it/English.htm