My favorite Edith Wharton book is probably The Custom of the Country, simply because Undine Spragg reminds me so much of my mother (she is currently married to her Raymond de Chelles equivalent). While all of the Wharton novels I have read are funny and painfully accurate to human nature, this one kept me chuckling ruefully to the very last page. The story is a rather hilarious (to me) character study of a Midwestern belle trying to use beauty as a verb to gain entry into New York society, becoming funnier and more depressing with every turn of the page. Undine is an extreme personality, a total narcissist, the type most people cannot allow themselves to believe exists. For anyone with a true narcissist in their lives, this book is a must-read. I am convinced Wharton must have known one intimately to write such an accurate portrait. Undine is given no more sympathy than she deserves, and neither are the men who succumb to her charms or the parents who allowed her to become the creature she is.
If you enjoy Henry James, have ever wished for a more empathetic Thackeray, or find Austen just a bit too precious at times I cannot recommend this book enough.