If its the private sector that you're interested in, I'm not sure how much of a bump the AU MBA would give you over an MA from SAIS. For a non-MBA program, SAIS still pulls in some big names like McKinsey, Bain, BCG, etc. and I'm not sure if those firms recruit at AU. That is not a knock on AU, but it just seems that premier private sector firms are more concerned with the "name" of a school. My impression is that public sector jobs are not really concerned about prestige.
You wanted to hear an alternate opinion, so there it is, but congrats on your offer! AU is a great school and graduating debt free is huge.
**Just re-read that you are interested in economic development work so my point is probably irrelevant!