BE VERY SPECIFIC
1) Comment on the campus and/or student life
When you visit a campus make sure to jot down a couple of thoughts. These could include something your tour guide said or something you observed about the campus (students, buildings, activities, etc). When asked on your application why you want to attend a particular school, you'll be able to touch on one of your thoughts so that your answer is specific and meaningful.
2) Read through the course catalog
Study the classes offered in your intended major and mention something about them. You might comment on the way the courses progress or a particular class you are looking forward to taking.
You might also want to say something about the way majors and minors are structured that appeals to you.
3) Study the school's mission statement(s)
What is the educational philosophy of the school and perhaps the particular department to which you are applying? Is there something about the philosophy that appeals to your own thoughts and hopes about your education?