Wow! Nice responses!

It is indeed a person to be pitied who does not feel the pull of the book.

I thought of a few more:

The Wind in the Willows, by Kenneth Grahame
Till We Have Faces, by C. S. Lewis

Actually, anything by C. S. Lewis. One of the most brilliant writers and philosophers or the twentieth century.

Also the modern socratic dialogues by Peter Kreeft:
Between Heaven and Hell
Philosophy 101, by Socrates
The Unaborted Socrates
The Best Things in Life
Socrates Meets Jesus
Socrates Meets Machiavelli
Socrates Meets Marx
Socrates Meets Sartre
Socrates Meets Descartes

I also like the books of P. J. O'Rourke. Great for the armchair political philosopher (such as myself). He wrote a slew of stuff, all of which is funny and thought provoking (All the Trouble In the World, Peace Kills, A Bachelor Home Companion, Parliament of Whores, Modern Manners, etc.)