This month, my book clubs read two books, both of which were highly acclaimed by the managers who read them.
The first is The Four Obsessions of the Extraordinary Executive, by Patrick Lencioni. It's a fable about management, with a self-assessment and some how-to's at the end. The fable takes about an hour and a half to read, and is very instructive. Good for all levels in your organization.
The second book was Career Warfare, by David D'Allesandro The book is ostensibly about succeeding in your career, but is really about becoming a good leader, and improving your organization. It's funny, and full of good ideas and great stories.
Both books generated great discussions, and are worth a look for you.