Also, I know most people think about college for the Alumni connections, but don't count out the crazy high school pride New Trier grads have and how that helps with the job search in their 20s.
I have never once found an New Trier connection to be useful for a job search. I haven't lived in the Chicago area in my adult life, so perhaps that is why, but I think most people by the time they are in their 20s have put high school behind them. The main exception to this is kids who went to boarding school like Exeter.