My favorite books: CLICK ON ANY MAGE TO ORDER
Autobiography of a Yogi by Paramahansa Yogananda is DA spiritual classic, he is the first yogi who came to the USA to tech the metaphysical part of yoga, kriya yoga. If thus is ONE book you need to read, this is it! Yogananda wrote commentary on Gospels and commentary on Bhagavat Gita, the holy book of Hindu religion. It will blow you away......
Sri Yuktewswar is the guru of Yogananda and he was an astrologer. His view of the world will rock you!
Dalai Lama wrote Art of Happiness, and many other books
G I Gurdjieff wrote Beelzebub's tales as a story that in a very sneaky (and humorous) way talks about human frailty and delusions as well as the larger Light of God.
Hafiz lived in ancient Persia, was a sufi, and his poems were used as spiritual textbooks.
Rumi was very similar too, almost lived as the same time as Hafiz. But Rumi was a famous scholar. Hafiz was just a baker boy...
Jacob Needleman is our contemporary, and head of Gurdjieff's groups. He wrote this book trying to figure out why Christianity was failing, and found out that lack of meditation and self reflections really hurts Christian churches, so people are trying to get back into it.