Hi Marie,
It seems to me that Waltham area is cheaper than Cambridge or Boston. I think you have to consider if you want to live in a suburb (and most likely have to depend upon a car) and live close by campus, or have the conveniences of a big city and rely on public transportation.
Brandeis is a school I do consider, since this is so far the only acceptance (still waiting for 5 schools!!) I got. More important, the interaction I had with faculty and staff was very positive. People I met and interacted with by email are open-minded, friendly and intellectual stimulating. Brandeis seemed to me a small scale university, with a personal touch (versus larger universities, large scale programs). The program I got accepted to seems to me an excellent fit - therfore I truly consider attending Brandeis. However, I do want to see what other programs and schools have to offer and am patiently waiting to hear back from the rest of schools/programs.
Judith