No new senators would be created, so no yielding 2% power, and Maryland and Virginia might get 1-2 more electoral votes and/or congressional representatives.
I would imagine that the main issue that would need to be resolved is jurisdictional...would laws passed in Maryland and Virginia apply to residents of DC? If so, it's conceivable that those states could influence Federal policy. What would happen if one of those states made it illegal to order a drone strike without the approval from one of their courts...could the President be arrested and charged in that state for violating that law?