Have you considered add-ons? I know people look for free usually, there is as possibly good replacement for free over at flightsim.to, a growing download community, or you might want to look at Drzewiecki Design.
I know one thing I can't stand in my home state, they have a tree right in the middle of the state house, which isn't right. I know politicians cause a lot of heat, but I'm sure they don't need a tree to stand in the shade under it that close! :) :)
Hope this helps. Drzwiecki Design does have a Washington Landmark pack, and I own it as well. It's worth it. :)
As far as a freeware add on for the Washington area goes, here's one right here, and looks pretty darn good if I do say so myself. https://flightsim.to/file/631/washington-dc-landmarks-pack Just extract into your community folder and should be fixed.
I just miss understood what you were saying on the other comment, and glad to offer help if I can now and hope I have with these suggestions.