WITH a swirl of honey-blond hair, feline green eyes and a blue bloodline (her great-grandfather was Marcellus Hartley, the 19th-century philanthropist, whose funeral in 1902 drew Andrew Carnegie and J. Pierpont Morgan), Lauren Remington Platt ticks off all the checkboxes of a successful socialite. She is frequently photographed at fashion galas and charity balls, including the recent M Missoni for OrphanAid Africa party and the fall benefit for the Memorial Sloan-Kettering Cancer Center.