The Bartimaeus trilogy by Jonathan Stroud (first book is the Amulet of Samarkand.) -- an astonishingly good trilogy.
The Secret Country trilogy by Pamela Dean
The Last of the Really Great Whangdoodles by Julie Andrews Edwards
Try "Of Human Bondage" by W. Somerset Maugham
I know, title sounds totally depressing. But it's actually a very good read; interesting, quick moving, and not what you'd think from the title. It's semi-autobiographical historical fiction -- so it sort of fits both categories. :) Any library...