I think reading classics is a great idea, here are a few that aren't commonly suggested but will serve you well in college and were very enjoyable in my opinion: Metamorphosis by Ovid, The Decameron, and Don Quixote. Few people get through Don Quixote because of the length but it's actually hilarious and easy to have a conversation about. Something I wasn't encouraged to do that I wish I had been was to read new books in my area of interest. I've recently been reading a lot about microbes and infectious diseases and I would definitely recommend that if you have a major, whatever it is (philosophy, economics, biology, etc.) in mind for college that you read recent literature on it.