"Are there very very good schools that I've left off, places like Northwestern, UNC, Binghamton, Houston, Rice, Stony Brook, Irvine, Indiana, Georgetown, Iowa, A+M, FSU, etc.?"
This is a minor point, but UNC's placement record is likely comparable to Ohio State, Wisconsin, and Emory. It would be rare but not unheard of for them to place at a very top school (Harvard, Berkeley, University of Michigan, Washington University). But they can place students at the other schools on that list--schools like Binghamton, FSU, A&M, Iowa, and so on. And, like other such schools, the reality is that many students aren't placed in two-twos (and that's true of even the very top schools).
http://www.unc.edu/depts/polisci/grad_placement.html