Considering that I attended three different high schools, I can offer a good bit of input on this thread:
School One: Elite Prep School
Everyone was a snob, and viewed people that weren't rich as inferior people. Granted, my family is pretty well off, but almost all of my friends come from meager backgrounds. I learned to hate everyone quickly, and became an as*hole and total jerk for a year (Not to mention I skipped classes, learned a whole bunch about computers during my absence, and commited some rather... violent... acts.) Needless to say, I was expelled at the end of the year.
School Two: Specialized School
For the school that I went to for most of my high school years, there were no groups. It was an all ADD, ADHD, and Aspie community. Sure, there were some people back in public school that were popular, and some were even disgruntled bullies, but all-in-all it was one happy, outcast family of 150 students and teachers.
Every single person in the school had fairly significant problems of their own, and it pretty much bonded everyone together. The teachers mostly understood how to deal with people like us. If not for this school, I probably would have never made it through high school and would only be a shadow of what I am today.
School Three: Public School
I returned to public school just for the intent to graduate early. I did fairly well socially and grade-wise. As for the people I hung out with, they were all either Partiers, Gamers, or Black people (who always had my back ). I did pretty good overall, I have to admit.