G.I. Gurdjieff's books (mostly "Beelzebub's Tales to His Grandson" and "Meetings With Remarkable Men") helped me much. It's hard for me to summarize them (they are full of meaning). Gurdjieff was a truly original thinker and searcher.
Robert de Ropp's "Warriors Way" and "The Master Game" are very interesting works by a student of Gurdjieff & Ouspensky. Indirectly, his life story in ("Warriors Way") puts much modern history into philosophical perspective.
Ram Dass's early books "Be Here Now" and "The Only Dance There Is" are sincere autobiographies of an interesting life which crossed from Western to Eastern.
"In Search of Secret India" by Paul Brunton is very honest and compelling. He recounts meetings with several men of real achievement.
"Gilgamesh", a Sumerian work recovered in the 19th or 20th century, is a story of friendship and other important issues.
Homer's "Odyssey", translated br Fitzgerald (maybe other translations are good), shows that man has changed little in 3000 years.
"The Origins of Consciousness in the Breakdown of the Bicameral Mind" by Julian Jaynes is very well thought out, and very integrative, though I suspect his basic thesis is not quite correct. His thesis is that a major shift in human consciousness occurred a few thousand years ago.
David Godman's "Be As You Are - The Teachings of Sri Ramana Maharishi" is a very well edited presentation of the words of an Advaita sage. This was the first "Advaita book" which I really connected with.
"I am That: Talks with Sri Nisaggadatta Maharaj" by Maurice Frydman (Acorn Press) contains great conversations with another Advaita sage. I consider this my most important book at the moment (2017).
"Great Swan : Meetings with Ramakrishna", by Lex Hixon, poetically and effectively renders the life of this sage. Implant the cover photograph in your mind's eye. In that photograph, what do you think he is feeling?
"The Truth Is", by H. W. L. Poonja, Prashanti De Jager (Compiler), is a large volume filled with obvious, yet deep and meaningful truth. Poonja (Papaji) was a student of Ramana Maharsi.
E. J. Gold's "The Human Biological Machine as a Transformational Apparatus" , among other things, contains a chapter entitled: "Bringing the Woman to Life" that contains the most poignant and well-expressed verbiage I've ever seen about the differences between man and woman.
Eckhart Tolle's "The Power of Now" is a wonderfully accessible and understandable account of a Western man who underwent a transformation which resulted in his freeing himself from past, future, and thoughts. In other words, he discovered his real Self.
Peter Kingsley's "Reality", and his other works, guide the reader to experience reality beyond what is possible with the rational world view we inherited from later Greece. His scholarship, open mindedness, and love for the teachings of Parmenides and Empedocles are impressive.