Have you read Down and Out in Paris and London by George Orwell?
You'll need a strong stomach for some of the descriptions of what went on behind the scenes in the Paris hotel kitchens, but it's a brilliant read, eye-opening and fascinating. Unforgettable - I read it a couple of years ago and often think about it.
"The Color Purple" by Alice Walker - an astonishingly well written, thought provoking book.
"Talking Heads" by Alan Bennett - absolutely brilliant! Not a novel, a series of monologues. Similar in tone to the Adrian Mole diaries by Sue Townsend (also strongly recommended). In particular, I recommend, "A Bed Among The Lentils" and "A Chip In The Sugar".
yy to the Alan Bennett - in fact anything by him Have you read his two volumes of (sort of) memoirs/diaries, Writing Home and Untold Stories? They are excellent. He's also written quite a few short stories/novellas too, which are all enjoyable.