Going over my reading over the last year or so I have to say the following titles have left the most impression on me.
I would highly recommend any one of the following.
Eat, Pray, Love: One Woman's Search for Everything Across Italy, India and Indonesia by Elizabeth Gilbert
Bones Of the Master: A Journey to Secret Mongolia by George Crane
Plan B: Further Thoughts on Faith by Anne Lamott
Seducing the Demon: Writing for my Life by Erica Jong
Jarhead: A Marine's Chronicle of the Gulf War and Other Battles by Anthony Swofford
And my all time favorites
Spiritual Enlightenment the Damnedest Thing by Jed McKenna
The Cliff Walk by Don J Snyder
Martin Eden by Jack London
Silence of the Heart by Robert Adams