The new Acropolis museum is totally mind-blowing. It is one of the best in the world and worth a visit on its own. You can then walk through the Plaka, but don't expect good value. We took the bus and the train for a 4 day pass. Others paid $87 for not much more.
Poor weather, but that is not the island's fault. Astonishing volcanic geology [ if you need a guide for this, give me a call :) ]. Again cheap public transport both to Oia and to the wineries. 6.40 versus tour prices over 10x as high. Oia has paint-me-paint-me vistas. The walk down the switchback past the alternative transport was entertaining. They are mules, not donkeys.
We gave Naples a miss. It is the dirtiest of the major tourist cities in Europe. In fact it represents all that is 'iffy' about Italy. So we went to Naples, on the bus and train, of course, and returned with the water taxi. Again a huge saving. Sorrento was utterly delightful.