I really enjoyed The Professor and the Madman, despite its flaws. I don't believe most of the brief history of English that Simon Winchester with which introduces his history of the Oxford English Dictionary, but I trusted and enjoyed the latter.
I love this delving into something obscure, finding letters and scraps of paper and the fate of Telephone Number One (the first major editor of the OED was friends with Alexander Graham Bell and was possibly was given the first working phone, which possibly remained in his attic to be burned by billeted soldiers one freezing winter during World War II). Bounty: the True Story of the Mutiny on the Bounty and The Longest Day (N.B.: D-Day is not obscure) remind me of that kind of painstaking effort.