You might be interested in the text books I use for my section of the Spiritual & Leadership Development course at Crown (Dr. Glenn Meyers teaches the other section). I find limiting the book selection to be a difficult task because there are so many life-changing, formative works that have been written throughout the centuries. The following, however, serve as either required primary textbooks or secondary reference/content materials:
The Pursuit of God: The Human Thirst for the Divine ~ by A.W. Tozer. "Faith is the gaze of the soul upon a saving God," Tozer wrote. To encourage that gaze, students write a reflective journal/prayer from a chapter a week.
The Celebration of Discipline: The Path to Spiritual Growth ~ by Richard Foster. Students use this book as a guide for learning and practicing spiritual disciplines throughout the semester such as prayer, solitude, worship, and, believe it or not, celebration.
A Tale of Three Kings: A Study in Brokenness ~ by Gene Edwards. One of the most interesting little books I've ever read, A Tale of Three Kings embodies many of the spiritual and leadership themes from our course.
In the Name of Jesus: Reflections on Christian Leadership ~ by Henri Nouwen. No Christian who has a role of leadership should make one more decision without wrestling with this book. The temptations for power and relevance and glamour are too great… even in the Church.
Secondary Sources: A litany of other books serve as resources for our course content throughout the semester. Some of the more resourceful include: The Imitation of Christ by Thomas a' Kempis, The Contemplative Pastor: Returning to the Art of Spiritual Direction by Eugene Peterson, A Grief Observed by C.S. Lewis, The Proslogion by Anselm of Cantebury, From Brokenness to Community by Jean Vanier, and Jesus on Leadership: Discovering the Secrets of Servant Leadership From the Life of Christ by C. Gene Wilkes