With kids, give Palazzo Medici Riccardi a miss.
Come for one room and it delivers completely: the Magi Chapel is a tiny windowless jewel-box where Benozzo Gozzoli covered every wall, floor to ceiling, with a single dense procession of the Three Kings — a glittering parade of brocaded riders, hunting leopards, and portraits of the Medici themselves threaded into the crowd, all gold leaf and storybook colour packed into a space the size of a large closet. It's the opposite of a vast cool gallery: total, immersive, almost claustrophobic richness, and entry is timed to a handful of people so you get it nearly alone. Beyond the chapel and a Baroque ceiling-gallery there isn't much — but that one room is the whole point and it's worth the stop.