I would like to nominate A Question of Upbringing, the first novel in Anthony Powell's Dance to the Music of Time sequence. I read these novels about 20 years ago and have always wanted to revisit them. Powell was a contemporary of Evelyn Waugh's and his books have a similar perspective. People might have grabbed this when it was free on the release of the entire series in ebook format; if not, it's $6.29 at Amazon and $6.40 at B&N. It also should be easily gettable at the public library.
Here's the blurb from B&N:
A Question of Upbringing (1951) introduces us to the young Nick Jenkins and his housemates at boarding school in the years just after World War I. Boyhood pranks and visits from relatives bring to life the amusements and longueurs of schooldays even as they reveal characters and traits that will follow Jenkins and his friends through adolescence and beyond: Peter Templer, a rich, passionate womanizer; Charles Stringham, aristocratic and louche; and Kenneth Widmerpool, awkward and unhappy, yet strikingly ambitious. By the end of the novel, Jenkins has finished university and is setting out on a life in London; old ties are fraying, new ones are forming, and the first steps of the dance are well underway.
"Anthony Powell is the best living English novelist by far. His admirers are addicts, let us face it, held in thrall by a magician."—Chicago Tribune
"A book which creates a world and explores it in depth, which ponders changing relationships and values, which creates brilliantly living and diverse characters and then watches them grow and change in their milieu. . . . Powell's world is as large and as complex as Proust's."—Elizabeth Janeway, New York Times
I also want to second Persuasion. I know P&P and Emma stone cold, but haven't reread this in decades. Am I the only person old enough here to remember when no one liked or read Austen? 'Cept me, of course!