This is a great non-fictiony book, best of the three in this set (author made it into a kind of trilogy). As long as you don't mind reading a little gore at times. It is non-fiction vignettes about events that occur to the author during his years interning at a hospital as he learns to become a doctor, if I recall correctly. This is hands-down the book I recommend the most when people ask for one. Many people haven't read it but it's amazing. Complications by Atul Gawande If you want something by the same guy that is more potentially-world-change-y, here is The Checklist Manifesto which I also really liked.

If you want one that people use in arguments read Michael Pollan's the Omnivore's Dilemma. It will change the way you think about the food industry in America. I like Pollan a lot.

For more fiction-y stuff that steers away from the for-sure-obvious picks I like Murakami's A Wild Sheep Chase. This book will fuck up your head a little bit but it's not Infinite Jest length.

Have you ever considered Godel, Escher, Bach: An Eternal Golden Braid? I haven't read it but it seems like it might be up your alley. I think it is on the long-term to-do list for me.

I would suspect you have already read Tim O'Brien's The Things They Carried.