Hey congrats on the acceptance! I'm in a very similar situation, actually. I just got accepted to the same program at Monterey, and am waiting to hear back from quite a few schools (including GW!).
It seemed that the admissions board was willing to push your deadline back a bit further than that? I'm not really sure how it works. That being said, Monterey may not have the D.C. "in the middle of everything" experience, but Monterey has close ties with the State Department, USAID, and many other NGOs. I got the impression that there is a high caliber of internship and networking opportunities, many of which are located in D.C. or NYC. Which concentration would you pursue?