Washington Area

Army: Class B
Air Force: Class B (with or without tie)
Navy: Khakis
Marine Corps: Service B or C, as appropriate 
Coast Guard: Service Dress or Wooley Pulley

Civilian:  Coat and Tie 

DC Social Events

Graduation Dinner and Other Socials:

Business suit for men; suit or dress for women

CONUS Travel

Military:  BDUs, ACUs, flight suits, or khakis
Navy personnel who do not wear BDUs or flight suits may wish to bring several pair of "wash khakis." 
Several social functions during this trip will require civilian casual clothing.

Civilians: Dockers and an open collared shirt

Some briefing rooms might be chilly so a light coat or sweater might be useful.

OCONUS Travel

Army: Class A and B
Air Force: Class A and B
Navy: Khakis, Summer Whites and Service Dress Blues
Marine Corps: Service A and B or C, as appropriate
Coast Guard: Tropical Blue Long and Service Dress Blue (Wooley Pulley optional)

Civilian: Business suit or Coat and Tie, as appropriate

**BDU, ACU, flight suit or khakis might be required**

A business suit for men and a suit or dress for women could be required for OCONUS socials.