For all the schools on your list, be sure to do a good job not just on your essays but also on the prompts and short answers in the supplements. Of special note: if there is a "Why us?" question and what you write will work for any other college, chances are it will not pass muster. Colleges want to know you are a good fit for their school and have a real understanding of it. To begin with, you will need to know enough about each school to be genuinely interested in attending. And then show those well-researched reasons in the essay in a way that demonstrates that each school is a good fit for you in terms of your intellectual, academic and personal interests. The "Why us?" essay is a unique opportunity. Make sure you put in the necessary time and effort.
For more information and advice on college essays, including selecting and developing a topic and insight from the deans of admission at MIT, Georgetown, Northern Illinois University and Williams College, see Chapter 13, "Essays," in College Admission: From Application to Acceptance, Step by Step.