Kids at FRA
Everytime I have visited the food court on the top floor of FRA T2 the childrens play zone outside McDonalds ( A room with a sort of lunar module construction and containing loads of soft rubber balls) has been well populated and generating a high decibel count. Would suit the lower end of your age range - good views of traffic from this area as well as the roof terrace outside but that would be cold in winter.