Although it should not be a limiting factor when applying to a school, cost is a major issue for many students. Depending on their family's financial situation, some seniors have to pay for college out of their own pocket, while others say that their parents are willing to pay the big bucks. Many rely on scholarships or grants from the college they will attend or from outside organizations. Everyone's preference for size is different. Many of my friends desire a large university atmosphere where there are lots of things to do.
Most people only consider schools that have a strong program in their area of academic interest.
For those who intend to study science, this is of particular importance because a school must have good lab facilities, opportunities for undergraduate research and professors who encourage student involvement in science-related projects. Going along with this, the faculty to student ratio is also significant. Many large schools will conduct lectures in large groups and have grad students teach recitations, where the class is broken down into smaller study groups once a week. Still another primary concern is a college's location. Some seniors are very anxious to get away from their parents and choose a college on the opposite side of the country.