Ok, we have:
Saks Fifth Avenue in Chevy Chase, Marilyn in handbags rocks (301-657-9000)
Neiman Marcus in both Chevy Chase and Tysons. I think NM in Tysons has a better selection of bags - my SA Tina McCauley (703-761-1600), can also find anything.
An actual Chanel boutique in Tysons Corner - Endra Nagaraj is great - but selection is well very very conservative.