It seems that the environment in Chicago might be bothering you a little. In this case, PLEASE strongly consider UCSD. My undergraduate school was in an environment I thought I might not like, and I didn't.
5-6 years is a long time to be somewhere you don't want to be.
I'm actually from San Diego, and am going to UCSD for my PhD this fall. Some of my friends have gone/are at UCSD, and they like it a lot. La Jolla is a very beautiful and safe city. The only downside is that UCSD is not a party school (but honestly, how is this a downside lol...).
Nice things about UCSD/California:
- University is literally on the beach.
- Driving distance to many national parks (the ones gracedavis91 said, grand canyon, and more).
- Great weather.
- Extremeley strong reputation in Biological fields.
- Will meet a wide variety of different kinds of people in California.
- Besides national parks, California has TONS of entertainment/places to travel (amusement parks, museums, LA, SF)
I really believe being happy outside of school positively affects your abilitiy to learn and to work. Since the issue obviously isn't program reputation, I'd say go for UCSD!