When we did some over spring break we were in warm climate so just a nice dress. There were boys in shorts and t-shirts and some kids just in jeans. I don’t think it matters much as long as you are clean and presentable, definitely much less formal than boarding schools. Honestly, the only people who stood out where the ones wearing logo shirts/sweatshirts of another college, in quite a few instances a rival institution. I always wanted to ask what sort of message are they trying to send. I think some very truly clueless and bought the shirt at the previous school visit during their tour. But there was a kid in OSU gear on our tour of University of Michigan and just about everyone was rolling their eyes. He may have been of the school of thought “any attention is good attention” but I would not recommend going that route. I wish I could have been fly on the wall when he walked into his interview.