Here are nonfiction books of unusual merit, that have informed my understanding of the human condition:
The Road to Wigan Pier by George Orwell
The Best and the Brightest by David Halberstam
The Memory Chalet by Tony Judt
The Promised Land by Nicholas Lemann
There Are No Children Here by Alex Kotlowitz
Dreadnaught by Robert Massie. (Worst book title ever; sounds like the book is about battleships, subject is how Europe blundered into World War I)
The March of Folly by Barbara Tuchman
Nickel and Dimed by Barbara Ehrenreich
My Lai 4 by Seymour Hersh
Boss by Mike Royko
History of Standard Oil by Ida Tarbell (hard to read today, but the book that began modern journalism; try the abridged version)