my top 40 book recommendations:

Of course, you can't read everything and everyone you might ask would recommend different books.  But, take these recommendations from me on the authority of someone who has read extensively (over 1,500 books) across a wide range of subjects, teaches critical thinking, and has developed a course of study for homeschooled children.  

1. A Guide to the Good Life by William Irvine
2. How Should We Live by Roman Krznaric
3. Predictably Irrational by Dan Ariely
4. The Stoic Art of Living by Tom Morris
5. Plato, not Prozac! by Lou Marinoff
6. Innumeracy by John Allen Paulos
7. Physics for the Rest of Us by Roger Jones
8. How to Think About Weird Things by Theodore Schick
9. The Elements of Moral Philosophy by James Rachels
10. Nichomachean Ethics by Aristotle
11. On Liberty by John Stuart Mill
12. Walden by Henry David Thoreau
13. The Greatest Show on Earth by Richard Dawkins
14. The Origin of Species by Charles Darwin
15. The Day The Universe Changed by James Burke
16. Basic Economics by Thomas Sowell
17. Classical Music by Phil Goulding
18. Art as Therapy by Alain de Botton
19. In Praise of Slowness by Carl Honore
20. Creative Thinkering by Michale Michalko
21. To Sell is Human by Dan Pink
22. The Nametag Principle by Scott Ginsberg
23. What to do When It’s Your Turn by Seth Godin
24. The More of Less by Joshua Becker
25. Decisive by Chip & Dan Heath
26. The Evolution of Everything by Matt Ridley
27. Practical Wisdom by Barry Schwartz
28. Man’s Search for Meaning by Viktor Frankl
29. Philosophy as a Way of Life by Pierre Hadot
30. Curious by Ian Leslie
31. How to Think Like Leonardo da Vinci by Michael Gelb
32. Being Wrong by Kathryn Schulz
33. Meditations by Marcus Aurelius
34. The Art of Happiness by The Dalai Lama
35. Stumbling On Happiness by Dan Gilbert
36. Sparks of Genius by Robert & Michele Root-Bernstein
37. A More Beautiful Question by Warren Berger
38. Obliquity by John Kay
39. Essentialism by Greg Mckeown
40. 30 Lessons for Living by Karl Pillemer