With kids, it depends on the day.
A jewel-box of green-and-white tiles, palm-frond ironwork and Moorish-inspired interiors that show Gaudí before he went fully fluid. It's small and tucked into Gràcia, so you get the genius without the Sagrada-scale queues. The catch: it's compact, so don't expect to fill a whole morning, and the Gràcia location is a bit off the main Gaudí trail.