ON ISABELA: LANVIN dress ($4,440) and LANVIN coat ($2,550), Saks Fifth Avenue, 5555 Wisconsin Ave., Chevy Chase, MD 20815, 301-657-9000. ON CASEY: TOM FORD cardigan ($1,590), HUGO BOSS shirt ($155), THEORY pants ($225) and TOM FORD bow tie ($250), Neiman Marcus, 5300 Wisconsin Ave. NW, 202-966-9700.