Naples home base

No need for a guide in Capri or Sorrento. Since you have three weeks, I would consider staying on the AC for a few days.
At Pompeii you can hire a guide on site if you desire, and transport is easy.

VERY helpful and thanks! So after boat to Capri, just walk around...no car needed there? Your suggestion about a night or two in AC is excellent. Best way to get there and do you have a nice spot to stay there?

I'll let one of the Capri experts advise, but that is my understanding.
For the AC, you can take a train to Salerno and then walk (10 min or so) to the ferry (Travelmar) to your chosen town.
I would look at pics and read up on them to decide what works for you, but we loved Cetara for its quiet and restaurants.

I would add Herculaneum and Paestum to your day trip options from Naples, enjoy!

For a trip last winter (not quite the ideal time of year for the Amalfi Coast), I opted to spend 20 nights in Rome, 7 nights in Naples and 4 nights in Salerno. I knew 7 nights in Naples would be short for me, and it was, so I'm glad you'll have more time there.

I really enjoyed Salerno, and hotel rates there are massively lower than on the Amalfi Coast, where I'm betting availability for this September/October could also be an issue. I do sort of expect to spend a few nights on the Amalfi Coast at some point. but Salerno is a very nice, non-touristy option. The historic center is atmospheric, and transportation to Paestum is good. Ferry trips along the Amalfi Coast would be a good possibility if you don't want to travel around on land too much. All reports are that bus transportation there is very problematic. However, I'm not sure about the ferry schedule in October.

Ercolano, Ischia, and Caserta are all excellent and easy day trips from Naples. Ischia can be a longer visit, should you choose.

In my earlier response I failed to mention how great a deal the Campania ArteCard is for folks planning stays of more than a very few days in the Naples area. It covers entries to all the excavation sites, Caserta, and quite a few places in Naples (including the Archaeological Museum). I bought the annual pass, so there was no need to try to cram the covered sights into just a few days; I just wished I had more than 7 days in Naples and 4 in Salerno!

The documentation says you can visit each sight twice; I didn't get around to testing that, but it would be advantageous at some of the larger spots like Pompeii and the Archaeological Museum.

The tricky thing about the ArteCard is actually buying the thing. I wasn't able to find a place selling the Campania version of the card. It turned out to be really easy to download the app and buy the card within the app. However, there were a couple of times when the app refused to open for me when I needed to use it for entry at a museum. It was a very good thing that I had written down all the numbers displayed when I bought the ArteCard. I was able to show those numbers to the ticket agents at the museums, and that worked fine. Be sure you record those key numbers, just in case. And I'd say don't waste your time trying to buy the card in person.

https://www.campaniartecard.it/365-abbonamento-gold/?lang=en

In the section headed "Discover the places you can visit with this card" you'll find links to lists of places that are fully covered (many important ones) and lists of places that are just discounted (I think 50%, and those are mostly less important sights).

I love Ischia. Easy ferry ride from Naples port. Stay at Castle Aragonese. Drink wine from their terrace. Spend a day at the termal pools. I thoroughly enjoyed Poseidon Gardens. I recommend staying three nights, minimum, to have two full days in Ischia.

Thanks bpgillman. Recommendation for transportation around Ischia? We take ferry there and.....rent a car? Thanks!