I understand that fit is the most important, but that's not exactly what I mean when I refer to safties. I probably should have clarified, so my bad. Anyways, correct me if I'm wrong, but I'd assume that given that the fit is reasonable (i.e. research matches your interests in both schools), a higher ranked school will be (relatively) more competitive than a lower ranked school. So restated, assuming all schools have similar research fit, what range of schools would an applicant have high probability (70%?) of acceptance given they are competitive (3.7+ gpa, 330+ GRE, 2+ years research including summer programs (eg. REU's)) for top tier PhD programs. Hopefully this will result in some different answers.