I can recommmend Giovanni of www.tourofitaly.com. There are many great review for him on the forum. We did a tour with him in June and it was a wonderfully memorable day. He seemed to know everyone and everywhere in the coast and made the day special for us. He is native and really allowed us to experience the area.

He picked us up at the port, arranged for a fantastic guide in Pompei and made it a truly special day.

To be warned, the Amalfi Coast is known for crazy driving and incredibly tight winding turns and he certainly lived up to that reputation.

I would high recommend him.