Wendy Wasserstein came to fiction late in life. The Pulitzer-winning playwright had published scores of scripts, essays, and even a children's book before she died of lymphoma in January at age 55. Her first novel is quintessential Wendy: bookish heroine (pediatrician Frankie Weissman, who's smart, single, and stranded), glam Manhattan settings (cocktails at Bemelmans Bar, dinner at Da Silvano, shopping on Madison Avenue), and stiletto-sharp satire (mostly of superrich, social-climbing ladies who lunch). But the Birkin-and-Botox babes wear out their welcome faster than last season's Prada, and the warm, witty Dr. Weissman disappears into the New York City skyline. Elements of Style could have used a smidge more substance.