Brigid Sweeney, Photo by Christopher Churchill

A Weekend In: Newport

    FRIDAY 4 p.m. The best way to soak up the opulence is free: The three-mile CLIFF WALK provides glimpses of mansions like the Breakers, once the Vanderbilts’ summer "cottage." Memorial Blvd. and Eustis Ave., 800-976-5122, cliffwalk.com.    7…