I love The Diddakoi by Rumer Godden and The Story of Holly and Ivy also by Rumer Godden. Also her books for adults are suitable for 11/12 and up - The Greengage Summer, Peacock Spring, The River etc. Love them all.
Other childrens' books I love are all the Little House on the Prairie books, The Secret Garden, A Little Princess, Tom Sawyer, Charlotte's Web, A Christmas Carol, Seven Little Australians, What Katy Did, Little Women, books by Elizabeth Goodge. All the Over Sea, Under Stone books by Susan Cooper. Narnia books.
When Hitler Stole the Pink Rabbit is great. The Endless Steppe. Boy in the Striped Pyjamas - all heartbreakers though. Mrs Piggle Wiggle stories are fun - and I lov eOscar Wilde's stories - like The Happy Prince and The Selfish Giant.
Enjoyed Harry Potter but the writing isn't very inspiring although the stories are a good concoction of folk tale and Enid Blyton school stuff.