You two seem to be comfortable discussing the subject with each other so we are a bit hesitant to jump in and offer some services, but let me toss out some ideas. If you are are limiting yourself to cruise line excursions then you have to simply decide among the choices. However, if you are open to doing things on your own (with some good detailed info) or booking a private excursion we can give you a basic idea of options. If you enjoyed Pompeii you might want to visit Herculanium which is nearby in the city of Ercolano. And then there are islands such as Capri (easy to do on your own) and the more obscure islands of Ischia and Procida (we do not normally recommend these places unless the traveler is really looking for something different). As to the Amalfi Coast (we have spent 2 extended vacations here) there are the fabulous cities of Positano and Ravello and also Amalfi. And then there is Naples itself which is actually somewhat better then many folks think and does have a fabulous archeological museum (which has many treasures from Pompeii).
Regarding Sorrento (not our favorite place) it is easy (and cheap) to simply take the Circumvesuviania Train from Naples. There are two trains per hour and it takes about 1:05 each way. Sorrento is easily explored on foot.
As to private excursions, they are expensive (400 - 550 Euros) but you get to set your own itinerary and get great service. One highly recommended private tour company is Rome in Limo Tours.
P.S. As to my personal expertise we have been to Naples on more then 15 cruises and have spent several weeks vacationing along the Amalfi Coast (we stayed in Praiano) with our own rental car.