Out of touch rich New Yorkers

I recently found a copy of the First Wives Club at the thrift shop. I had no idea it was a book and it was as delightful if not more than the movie. I also love books about out of touch rich people and the underdogs in their orbit – think Devil Wears Prada, Nanny Diaries, etc. Anything about NY private schools always seems up my alley too – think Small Admissions. Any suggestions for other books in this vein?