Although it would depend on ages of the children, (if any) we prefer going to places like Magna science museum, Eureka (a childrens exploration centre), and museums rather than loud noisy theme parks. We've spend many Saturdays as a family going to the Lake District and if you go to the lake that's furtherest north, Ulswater, it's very quiet and deserted. You can find a really nice secluded spot by the lake, kids paddle in the lake while dad gets the disposable barbeque going (-marinated chicken tikka and masala fish!), then a leisurely boat ride and a light trek to the top of a water fall followed by a walk in the woods. Ice creams on the way home. The best thing about it is thats your not surrounded by shops, people, music etc. Just simple, calming nature.