We had a very satisfactory daytrip to Capri from Sorrento (5 nights), perhaps because we had no interest in the Blue Grotto. Walked five miles at least. If I did not have to hump my suitcase through pedestrianized mileage, I might be willing to spend a night on Capri. But really, it has a lot of asphalt for a place that most posters consider a slice of paradise!
It is true that Sorrento is the best location in the area for daytrips, but I agree that 8 nights are too many. Sorrento (despite the romantic name) is indisputably a purpose-built, postwar, reinforced-concrete resort product. But it is built on a sheer cliff, so it has only one tiny beach, which is located right between two diesel-fumed marinas! This sounds harsh, but we are NOT sorry we spent five nights there, for daytrips. Our luxury cliff-front hotel (Ambasciatori, paid extra for balcony and Vesuvius view from our bed) had private Gulf swimming platforms accessible from the hotel elevator. Despite double windows and (needed in May) fierce air conditioning, we sometimes heard ferry horns.
Circumvesuviana without luggage was ideal for Pompeii, Herculaneum, and other ancient sites. Alas, Sorrento is so far from Paestum that we had to discard our plan for a high-season daytrip there. It would be a really long day, even if you got the right ferries via Salerno. It is hard to download all company ferries for Sorrento. And company A will not tell you, hey company B leaves 35 minutes sooner!
We took the gritty Circumvesuviana to Sorrento, but the jammed conditions with full-sized luggage were punishing. Combined with the overpriced 15 Euro taxi to the hotel, it was easy to tell the Ambasciatori to hire a 100 Euro Mercedes to take us back to the Naples rail station, charged to our hotel bill. (Old prices, higher today.) Same local surface travel partner provided our 8 hour daytrip by sedan to Positano, Amalfi, and Ravello.