HIGHLIGHTSOn Saturday night, docu-series “Welcome to Sweetie Pie’s” (OWN at 9 p.m.) chronicles the adventures of St. Louis restaurant owner Robbie Montgomery, who once worked as a backup singer for Ike and Tina Turner. Sunday talk shows: “Platts Energy Week” (WUSA at 8 a.m.) interviews Bank of America’s Jonathan Plowe, Rapidan Group’s Robert McNally and Rice University’s Amy Jaffe; “BioCentury This Week” (WUSA at 8:30) features Amicus Therapeutics’ John Crowley, WMD Center’s Lynne Kidder and retired US Air Force Col.