I'm enthusiastic about the idea, but I think the approach is flawed. "Cities over 100k" misses the real regional keystones (some of which are really counties, not cities), so I'm seeing ones that I would expect to be there missing. And the ones I do know aren't the best represented.

Specifics: Alexandria is basically DC, and probably shouldn't be included without several places that are missing in Maryland. I have no idea what Baltimore's icon is supposed to be (edit: wait, is that supposed to be the Domino Sugar sign?), and while the Capitol dome is a decent choice, the Washington Monument would probably work better as a symbol of Washington.

This could really be a launching point for crowdsourcing a more handcrafted set, though.