We did all three comfortably in one day on a Princess Excursion. We probably paid a little more than we would have doing it on our own but it was our first time there and the convenience and peace of mind made it worthwhile to us.
On arrival at Naples we took the hydrofoil to Capri where we spent several hours; then another hydrofoil to Sorrento where we had a leisurely lunch in a seaside restaurant and time for walking around and shopping. Then a motorcoach to Pompeii and Herculaneum. There was ample time for a guided tour and then time on our own. And there was even time for the obligatory stop at a small Cameo factory and showroom. All in all a very full and satisfying day.