Solo, Basilica dei Frari works.
This towering brick Gothic church frames Titian's blazing 'Assumption of the Virgin' on the high altar — designed so the painting hits you from the door — plus Bellini's serene triptych and Titian's own tomb. It's one of Venice's great art-in-context experiences and rarely crowded. The catch: there's a (small) entry fee for a working church, and it's an art/architecture pleasure more than a casual photo stop.