Since Bob Morgenthau, known as “The Boss” by many of his staff, has decided not to run again, the field seems to be narrowed to two major candidates: Cyrus Vance, Jr. and Leslie Crocker Snyder. Both are experienced people who know criminal law. Snyder, who has been a judge and Vance, a former Manhattan A.D.A and criminal defense attorney, are both formidable candidates.