I had an intern in my office this summer who said that she went to the University of South Carolina because she got rejected by Appalachian State... :wtf: I am not sure if that was just a really weird aberration, but I still think of both USC and Clemson as being good schools.
You really shouldn't group USC and Clemson together - though people do. Clemson is actually a much better school than people realize. I believe it is a top 20 public school. USC on the other hand is a very generic, big SEC school. They have one excellent program (Int'l business) but otherwise do not stand out.
Clemson is much more difficult to get into. My daughter had friends who were flat denied at Clemson who got significant scholarships to USC.