Fast answer
A good Varenna ferry day starts by choosing the crossing sequence before adding villas, extra towns, or dinner plans. For most first ferry days, begin with the Varenna pier and decide whether Bellagio alone is enough. Add Menaggio or Cadenabbia only when the western shore is part of the real plan, not because the map makes it look close. Ticket choice matters, but reducing crossings is often more important than buying a broader pass. Ferry timetables, tickets, queues, weather, train returns, villa access, parking, and fallback planning should stay visible until the travel date.
If you only do one thing
Start with one clean Varenna-Bellagio crossing plan, then add Menaggio or Cadenabbia only if ferry timings, tickets, weather, and return logistics still leave slack. If the day depends on Milan train return or villa access, keep the ferry plan lighter.