Lady Bird is ill; Lynda and Luci Johnson, with Warrie Lynn Smith, fill in at social events at the White House; Peter Benchley presents "Jonathan Visits the White House, accompanied by Jonathan and 30 other children; cute stories about children; performance by National Ballet Company; presentation of Margo Jones awards; account of day's events; personal comments about Luci Johnson; House passed Civil Rights Bill; LBJ and his mood