Congrats on what are two very, very good offers. 30k a year is amazing; as previous posters have said, I would not take that 10k a year lightly. That said, I believe there are major advantages to being in a real city (Charlottesville is very fratty and not very interesting), and I find Chicago's faculty to be very exciting (and I think their focus on rigorous interdisciplinary work is both unique and very appealing). You should visit both.
If one has not heard from Chicago , should one simply assume that one has not gotten in? Did those of you who've heard back from them get emails or letters?