Not really non-fiction, but Zen and the Art of Motorcycle Maintenance is always a good read. Also if you're just interested in 'stuff', Plato's The Republic is very worth reading :
My reading list is already probably a decade long (I'm a slow reader). I've recently started to abandon books that don't grab me after an hour or so and I'm wondering why I didn't do this years ago. Previously I finished anything I started.
Took a philosophy class in college, where we read Zen and the Art of Motorcycle Maintenance. Got a big shock about halfway through the book when I closed it and saw "Non-fiction" on the spine!
https://en.wikipedia.org/wiki/Zen_and_the_Art_of_Motorcycle_...
https://en.wikipedia.org/wiki/Republic_%28Plato%29