Itinerary suggestion

You're leaving less than 3 hours in the Athens airport. At Athens, you'll have to go through passport control, collect your luggage, and then check in for your flight to Italy and go through security. If your flight arrives on time and so does your luggage, that should be plenty of time. But you never know. If you have any delay or if your luggage goes astray, you could miss your next flight and then neither airline is likely to be very helpful. You'll be stuck scrambling to buy full price tickets on the next available flight that isn't sold out. I'm not a gambler, so I'd spend a night (or two) in Athens and then continue to Naples.

Where you stay on the Amalfi Coast depends on when you'll be there and what you want to do there. Do you want to sightsee - Capri, Pompeii, Paestum, or do you want to relax and enjoy exploring the coastal towns and the beaches?