Preoccupations of a privileged life, from bliss as a Marine brat in faraway places (Peking, for one) through three upwardly mobile marriages--the last, of course, to Vincent Astor--to dedication in the form of the Astor Foundation. But since Mrs. A. tends to play down the drama and highlight the stage settings (from the Italian castello to the Berkshire hideaway), or simply to reel off 20-year-old guest lists, none of this will mean much except to the small remnant of socialite-watchers. Husband number one was wed at too early an age, and the whole thing ended in disaster; number two died after 20 happily-married years, leaving Brooke lonely. It was then that Vincent Astor entered the picture, proposed precipitously on the basis of such commonalities as ""mutual friends,"" and eventually won her hand--though not, one suspects, her heart, since love is never mentioned and comfortableness seems to have been the rule during their eight years together. After Vincent's death she inherited the Foundation and membership on the boards of a half-dozen prestigious New York institutions, including the Metropolitan Museum of Art and the New York Zoological Society. But even these late-come charitable involvements have a slightly frivolous note, with Mrs. A. steering the Foundation toward building parks (""outdoor living rooms"") in the courtyards of low-income housing developments to make the residents feel ""at home."" One suspects that she equates coziness with tastefully arranged surroundings, and that, in essence, is what her memoir provides; but her stance as ""Public Monument . . . in the name of Vincent Astor"" seems a relic, too, from a bygone era.