Thank you, everyone; you've given us some great options to consider!

Regarding Sorrento weather in winter, though I don't see your travel dates so this may be moot, I stayed for several days the week before Christmas and loved it, did not find it too cold at all, daytime or evening. It was almost empty of other tourists, shops & restaurants were decorated for the holiday and it was families out & about so had a nice homey feel to it. I recommend a visit that time of year.

Sorrento... for a fabulous sea view, stroll about 10 minutes up hill following the ocean... many hotels along there have little bars & restaurants on their rooftops with stunning views!! I like to be on the water side of the main road... right on the cliffside!

The view from Naples's Castel Sant'Elmo is, IMO, spectacular.

Skip Sorrento, it is not pretty and only useful as a hotel base for part of a trip around the Amalfi Coast.

Definitely visit the Museo Archeologico Nazionale di Napoli before visiting either Herculaneum or Pompeii as this is after all, where a lot of the treasures from Herculaneum and Pompeii are now stored.

When you visit Herculaneum and Pompeii you will then be able to fully imagine what life use to be like.

We self-guided ourselves around Herculaneum but took an excellent tour with Walks of Italy for Pompeii, which commenced after lunch (2pm ish?)and lasted for 3 hours. Our tour guide was incredible and had previously worked at Pompeii for 10+ years. More information can be found here: https://www.walksofitaly.com/pompeii-tours.

I think whether to visit the archeological museum in Naples before or after visiting the actual archeological sites is a matter of preference. Some people prefer to visit the museum first, so that – as MissMandy suggests – they can more easily visualize what the sites were like. I visited the museum later, and was glad to be able to visualize the artifacts in context. Neither order is right or wrong, IMO; it depends on the person.

And IME, a guide is not necessary for either Herculaneum or Pompeii – it depends on how much you are willing to read in advance, whether you use the audio guides (I thought both wonderful), etc.

Thanks so much, everyone!