10 days for ALL of Campania. Naples deep (3 days), Pompeii + Herculaneum + Vesuvius (1.5 days), Amalfi Coast complete (3 days — every town + Sentiero degli Dei), Capri (1 day), Ischia OR Procida (1 day), and Caserta (Reggia) or Paestum (Greek temples). The complete southern Italy experience.
Each day is a logical geographic loop. Mornings for sights, afternoons for food, evenings for aperitivo.
Naples deep (3 days) — add: Catacombs of San Gennaro, Certosa di San Martino (the view + Baroque church), Museo di Capodimonte (Caravaggio, Tiziano). Street food tour: cuoppo fritto, sfogliatella, baba. Ischia (1 day) — the thermal island. Giardini Poseidon (thermal park, 22 pools). Castello Aragonese. OR Procida — Marina Corricella (the most colorful harbor in Italy). Reggia di Caserta (half day) — the largest royal palace in Europe (1,200 rooms). The park: 3km of fountains. Cilento coast (1 day) — if going to Paestum, continue south: Agropoli, Acciaroli (Hemingway stayed), Camerota beaches. UNESCO Cilento.
Best time: April-June, September-October. Book skip-the-line tickets for major attractions.