Lucie, yes, I live in the city, but I was also thinking about friends in Lower Merion. My experience was that there was a fair amount of apparent diversity at the private school – lots of kids of color, and a fair number of kids of all races on scholarships – but in fact the attitudes and frames of reference of the families were virtually identical, with only a few outliers. (I have posted elsewhere about the African-American scholarship boy who felt called to testify in public about the immorality of homosexuality, and the intense effort devoted to counseling him and his family into the school’s mainstream.) The public school had a dizzying variety of backgrounds, languages, educational expectations, politics, cultures, and, yes, intelligence. The median SAT score (1600 scale) at the private school was around 1300, and there was probably only a handful of students with scores below 1200. The median SAT at the academic magnet public school was 1100.
The public school aimed for 100% college attendance, but never quite got there, and military enlistment was a real option for many seniors. The private school sent a kid to one of the service academies about once a generation. That’s part of what I mean by “diverse in every respect,” and I think it would apply to Haverford or Baldwin vs. LM or even Harriton.