Immortal Life of Henrietta Lacks is one that I would second. At heart it's about the ethics of medical research, but there is a lot of background that really fleshes out the Lacks family and what AA life was like in Baltimore in the early 20th century.
If you want something a bit light-hearted, you might look at
Desperate Improvisation. It is a history of the WPA American Theatre Project during the Great Depression. All of the drama of actors and politics.
For something truly unique (and admittedly, not for everyone), there is
Radioactive, by Lauren Redniss. It is a biography of Marie Curie, but it is also an art book. It is written rather like a graphic novel, with the drawings taking equal billing with the text. Look at the preview on
Amazon; you really can't get it until you see it.
Operation Mincemeat is excellent. It's a history of a particular bit of espionage that was done by the British during WW2; they planted false intelligence reports on a dead man and deliberately put him where the Nazis would find him.
If you don't like gruesome, I'd skip
Devil in the White City. It's a very good true crime book, IMO, but it does dwell in detail on the serial killer's methods of getting rid of the bodies.
One book I've been recommending quite a bit is
Crashers by Dana Haynes. It's fiction, about an NTSB investigation into a plane crash (and the descriptions of how they go about that are very good and apparently very accurate, which I found fascinating.) It's one of those books where the reader knows what happened up front, but the suspense lies in whether or not the good guys will figure it out in time to stop it happening again.
