I go to a pretty preppy university in the city, so it's very, very rare to see people dressed in sweatpants going to class unless they're athletes. Generally "dressing down" is frowned upon by other students. Girls usually wear skinny jeans, Ugg boots, or ankle boots with layered tops or grandpa sweaters or crisp button-downs. For coats, the trend is long coats, usually double breasted. In the summer, sundresses with an airy cardigan and leather flip flops (never rubber) or flats. Many students come to class in business casual clothing, not because they're trying to fit in - just because majority of the students also juggle an internship or part-time job.