Venice has multiple overlapping passes. The transport pass is essential. The museum passes? Depends.
Plan your Italy trip →ACTV vaporetto passes: 24h (€25), 48h (€35), 72h (€45), 7-day (€65). Single rides are €9.50 each. If you take 3+ rides in a day (you will — Venice is a water city), the day pass pays for itself immediately. Non-negotiable purchase for Venice visitors.
Musei Civici pass (MUVE, ~€35): Covers Doge's Palace, Museo Correr, Ca' Rezzonico, Ca' Pesaro, Museo del Vetro (Murano), Museo del Merletto (Burano), and more. If you visit Doge's Palace (€30) alone, the pass is nearly justified. Add any other Civic Museum and you're saving.
Chorus Pass (€14): Access to 16 churches with art (Frari, San Polo, etc.). Each church charges €3.50 individually. Visit 5+ and it saves. Most visitors see 2-3 at most.
The city's "super pass" bundles transport + museums in various combinations. The website (veneziaunica.it) lets you build custom combos. The math works if you're a heavy museum visitor. For most visitors: buy the ACTV transport pass + Doge's Palace ticket separately.