Thanks, Gary.
I guess I should've clarified in my initial post that I understand that, by the letter of the law, there's no mention of access to contract lounges for *A members. However, given that there is no SAS lounge at IAD, I was hoping that others might've experienced some wiggle room given that the NW lounge is far closer to the SAS action.
As I say, either way is fine. Thanks again, Gary, for your post!