We visited the eight WHS in Southern Italy in September 2008. We stayed one week in Sorrento. We went to Naples and to Pompeii/Herculaneum by train and did all other WHS by rental car. Sorrento is perfect if you want to have one central base for the sites in Campania.
The small local train 'Circumvesuviana' connects Sorrento, Pompeii, Torre Annunziata, Herculaneum and Sorrento. It's only about one hour from Sorrento to Naples. More information and timetable on the website:
http://www.eavsrl.it/web/en There is much traffic along the coast between Naples and Sorrento and they all love the sound of their car horn. But in general, driving in Southern Italy was not as bad as I expected. The route along the Amalfi Coast can be challenging, because of the narrow and winding road, the traffic and the oncoming buses. And there is not much space to park, so we were very happy with our small Seat Ibiza.
Our highlights of the Amalfi Coast were Positano (a really spectacular setting), Amalfi and Ravello. Amalfi has a relatively large car park. Ravello (best by public bus from Amalfi) offers wonderful views to the coast from the garden of the Villa Cimbrone or the Villa Rufolo. The Oscar Niemeyer Auditorium also looks interesting (it was not finished on our visit):
https://www.google.at/search?q=oscar+niemeyer+auditorium+ravello&biw=1680&bih=786&tbm =isch&tbo=u&source=univ&sa=X&ved=0CCEQsARqFQoTCL3JlpuJiMYCFYO8FAodxQsAgQCilento/Vallo di Diano was a detour on our route from Sorrento to Puglia. Paestum was impressive, the museum is also interesting.
Puglia/Basilicata was quite and relaxing, compared to the Gulf of Naples it was almost deserted. The most lively place was Alberobello, we stayed there for four days. It's rather busy and touristy but we liked it. Actually we wanted a more central base, but the lady at the tourist office recommended to rent a Trullo, really a lovely accommodation.
From Alberobello it was about one hour to Matera and 1.5 hours to Castel del Monte.