Nostell Priory

Further afield than many of the out-of-town attraction mentioned here, Nostell priory (about 16 miles/45 mins drive) is an18th-century architectural construction with Adam interiors, fine collections and landscape park

From their website:

"Exceptional collection of Chippendale furniture designed specially for the house
Impressive range of paintings, by Breughal, Holbein and Angelica Kauffman
Lakeside landscaped gardens
Adventure playground and remarkable dolls house for children to discover
Over 121 hectares (300 acres) of parkland to explore
One of the finest libraries in the National Trust portfolio
...18th-century Robert Adam Obelisk Lodge and Boat House restored. Obelisk Park reopened to the public. Rolling series of book exhibitions based on the newly catalogued library."

Read more here: www.nationaltrust.org.uk (link takes you direct to the Nostell Priory Page).