With kids, Galleria dell'Accademia (Michelangelo's David) works.
Go for the Prisoners as much as for David. The four unfinished Slaves, half-trapped in raw marble down the approach hall, are the real taste payload — you watch figures fighting their way out of the stone, and they reframe the polished David at the end of the room. David himself rewards a slow circle: the oversized right hand, the tension in the neck, the way the back is as finished as the front. The honest catch is scale of visit, not scale of statue — beyond these two things the collection is thin and short, so the €16 lands as fair only if Michelangelo's hand is what you came for.