Some of the week's highlights TONIGHT JCC FORUM Diplomat Dennis Ross at Collegiate's Oates Theater. 545-8608. TOMORROW AIMEE MANN Richmond-born singer-songwriter at The National. 612-1900. THURSDAY-SATURDAY BLUEGRASS FESTIVAL Virginia Folk Music Association event at Chesterfield Fairgrounds. 347-2925. FRIDAY DESIGNER HOUSE GALA Symphony Designer House gala preview at Tara II, 5511 Cary Street Road. 784-4779. SATURDAY BALD EAGLE HABITAT and Raptor Valley grand opening at Maymont. 358-7166, ext. 310. ALSO SATURDAY DAEDALUS QUARTET Rennolds Chamber Series opener at VCU Singleton Center. 828-6776. SATURDAY, TOO YES, VIRGINIA -- DANCE Contemporary dance showcase at Grace Street Theater. 828-2020.