The sweet spot in the title of Amy Poeppel’s fourth novel refers to a grungy Greenwich Village bar, a beloved neighborhood fixture with battered wood floors, rickety tables and a pungent smell of beer.

There are the rich and there are the very rich, and while the very rich exhibit varied demographic characteristics, the family at the center of Jenny Jackson’s sparkling debut novel, “Pineapple Street,” is of a highly specific sort: the pedigreed, never-touch-the-trust-fund-principal, tennis-playing, old-money-Brooklyn WASP.

Language is failing Beryl Dusinbery. She is 99 years old and having trouble retrieving words. “One minute she has a word, then she hasn’t. Where does it go?” Conversely, Shimi Carmelli, 91, can’t forget.