Any book that you like.
I am particularly interested in reading some good non-fiction.
Crisis of Conscience tops my recommendations, I think it is one of the best books I've ever read. But you don't have to recommend apostate books.
Currently I am enjoying Dale Carnegie's How to Win Friends and Influence People. I am enjoying it and trying to take the advice to heart - namely, don't be so negative!
Any books that would help me to grow in my understanding of that mysterious creature commonly known as "woman" would be helpful also!