Is it too much to attempt both in one day, given that we have a cruise stop in Naples?

Hi A,

It's possible.

You can take a ferry from the docks to Sorrento and then the Circumvesuviana commuter train to Pompei Scavi.

The CC train will then take you to Naples Garibaldi (Centrale) station from whence you take a cab back to the docks.

Have you considered spending the day in Naples?

The Archaeological Museum has most of the good stuff from Pompeii.

I'd skip Sorrento altogether, but I'd add Herculaneum. It's completely different than Pompeii, so they complement each other. If you've got some extra time, go to Amalfi instead of Sorrento.

Sorry wasn't paying attention - you don't have time for Amalfi, plus you'll see the ocean from the boat! I still love Herculaneum...

Pompeii is really a day trip out of Naples - I dont see the point of visiting Sorrento - you will be seeing plenty of coastal towns on your cruise. Sorrento is more of a jumping off point for other destinations (Capri, Amalfi Coast, other nearby villages) than a major scenic destination on its own. Id recommend seeing a bit of Naples (including a bite of Pizza) if you wind up with extra time after your Pompeii visit. I found my Pompeii day to go surprisingly fast. I left the site to enjoy a lunch at Zi Caterina (a little way outside the Sanctuary entrance - left on Via Roma as you leave) - fortunately the guard didnt make me pay reentering the site. The food was excellent and good value - the best fritto misto I had on the trip, a great range of local wines, and a fine antipasto display. Even had a corny singer serenading the guests.
http://www.zicaterinapompei.it/indexen.aspx

I agree not much to see in Sorrento. I would do Pompei and Capri/Blue Grotto - both were amazing. Both easy to reach from Sorrento.