The strange lives of the Mitfords is what makes them fascinating. Can't argue with the comments from Ada about the awfulness Diana, Nancy and Unity - all true but they ARE intriguing and unique and each in their own way a window on history.
Mitford books in order of preference for me :
Letters Between Six Sisters, Hons And Rebels, In Tearing Haste, Wait For Me, A Life Of Contrasts
The biographies I've read by Thompson and Lovell were biased I thought
Also Immortal Life Of Henrietta Lacks and Last Act Of Love - brilliant
Another Bullshit Night In Suck City by Nick Flynn
Shantaram by Gregory Roberts
A Million Little Pieces by that guy who was discredited by Oprah
oh gosh
The Things They Carried by Tim O'Brien - Vietnam memoir
My Traitors Heart by Rian Malan - Apartheid memoir
The Man Who Mistook His Wife For A Hat - Oliver Sacks (neurologist memoir)