Now that DS is registered, I suggest that he contact Admissions to try to customize his trip so that he can get the most out of it. My DS asked to be paired with a cadet who is majoring in engineering and is on the baseball team. He also asked for an interview and to attend a baseball team fall practice. Admissions replied that they will try to accomodate his requests and that he should contact the baseball coach about observing the practice. He's not sure about engineering as a major, so the visit is a good chance to learn more about it. We've heard that time management is critical, so being paired with a baseball player will help him learn how the players juggle the time and energy commitment to the sport with everything else. No guarantees that his request for the pairing can be accomodated, but I don't think it hurts to ask and could make the visit especially helpful.
We visited the campus in February, so he will make the trip by himself. If I hadn't been there before, I would want to visit the campus with him. The Navy has an interesting submarine museum in nearby Groton with tours of a retired submarine available. That could be a way to spend the afternoon.