I wasn't going to add anything to the recent posts, but then the bird 
decided for me.  

Yes, there are urban (or at least semi-urban) Cooper's Hawks.  I've been 
seeing an immature one fairly regularly for the last few months out my 
office window, which looks out to the intersection of D and 18th Streets, 
NW.  It decided to make an appearance just a few minutes ago.

At least one Red-tail is regular in this area, too.

Jason Waanders
NW DC
jwaandersATstarpower.net