The reason I think these are more valuable than the pop psychology/business airport books is they don't operate under the pretense that the world's great truths can be boiled down to 240 pages. Rather, learning about people's experiences and stories on there own terms helps you develop a much more nuanced worldview.
For example, I'm reading The Battle Cry of Freedom, an overview of the Civil War, and it's astounding how much more insight a book about something 150 years ago offers into today's society than just about any of the Gladwell genre stuff.
Thats the period I was least interested in going in, but have ranked as the best History book I've read.
"Excuse me, sir...": ftp://www.fourmilab.ch/pub/etexts/www/gergel/isopropyl_bromide.pdf