Here is a list of Safehouses that you can go into to train to 200 skill caps. All these safehouses have 100% Safe in the name, which is noticeable on the map.
S.O.D. Section 1 Headquarters (36,27), S.O.D. Stadium Center (19,47), S.O.D. Northwest Rest & Recharge Barracks (23,98), S.O.D Section 2 Headquarters (35,80), S.O.D Section 3 Headquarters (41,116), S.O.D. Northeast Rest & Recharge Barracks (48,108), S.O.D. Northeast 100% Safe Zone (55,143), S.O.D. POL (Petroleum, Oils, & Lubricants) Storage (28,135), S.O.D. 2nd Area Storage Facility (44,98), S.O.D. Mess Hall (58,95), S.O.D. Research Facility (38,147), House of the Rising S.O.D.'s (36,50), S.O.D. Correctional & Disciplinary Barracks (34,42), S.O.D. Research & Development Facility (32,34), S.O.D. Midtown CIC (33,90), S.O.D. Fort Douaumont (22,146), S.O.D. Bomb Shelter (41,16) & S.O.D. Dead Letter Post Office (9,144).