The Children's Museum of Manhattan at 212 W 83rd St is perfect when weather turns and you need to entertain kids for 2-3 hours comfortably, though you could easily stretch it to 4 hours if kids are really engaged. Admission runs around $14-16 for kids, $12-18 for adults depending on current pricing. Exhibits are hands-on and educational without being boring.

PlayWorks area is great for toddlers, and art studio lets kids create stuff they can take home. Small café inside if you need snacks. Much less overwhelming than bigger museums with kids in tow.

1 train to 86th St, short walk west. Weekdays way less crowded than weekends.