Hi all--
For those of you wondering about the "sense of community" at GPPI-- in my experience, even thought it's a large cohort (100+), they have a lot of social events and everyone seems to know each other and get along really well. They even have a GPPI Prom. Professors are also accesible and some even go out of their way to help you (e.g., holding review sessions for exams without time limit). It's very expensive thought and that would be my main "con" for not attending GPPI. But I would not worry so much about the sense of community.
Best of luck to everyone!