Hop-n-Play, San Bruno

Hop-n-Play's indoor playground extends beyond the usual dimensions of fun. Apart from being climbable, slidable, and bouncable, nearly every play piece is also moveable. Toddlers can ride balls suspended from a spinning palm tree, or balance inside a slowly rotating hamster-wheel. Flowing water even makes an appearance, cascading down a tiny slide that's encased in clear plastic to prevent anyone from getting wet or ruining their makeup.

But each unique and safely padded attraction does more than entertain. While romping and running under the watchful eye parents, kids develop their muscle coordination and sense of space. And they can develop them late into the evening—families can show up ready for bed during the last business hour of the day, known as "pajama play."