I am in a somewhat similar position with the same scholarship offer from Kellogg, an admit (no $) from CBS and a long-term girlfriend who will likely be in NYC for the next 5 years (residency). I prefer the Kellogg location/culture, consider the career options to be on-par (although I am not interested in AM), and the personal side obviously pulls me to NYC.
I have asked CBS if they will match, and recommend you do the same if you have not already. I think there is some hope, as they have distinctly avoided saying "no" to me, and are stringing me along a bit. I think they would have to come back with ~$70K+ to tip the balance towards CBS. The reason I am thinking about it this way is that I know that a huge debt load would really start to weigh on me as it builds throughout my 2 years. I want the full MBA experience, which means some extravagant spending during school, and think the scholarship would make that possible. I also like the idea of having additional financial flexibility post-MBA, which would allow me to take an interesting startup job that covers my expenses but would not support $1500+/month in b-school debt.
Agree with others that it is an inherently personal decision, but hope my perspective is helpful.