My S did one this winter and many of his friends also went to scholarship weekend. For my S, his was a one day competition. They had activities for the parents and the students. The students spent 1/2 of the day writing essays and interviews and the other half was devoted to the honors program and the students specific major.
Some of his friends went for a weekend and that was a student activity and the parents weren't involved. He said that is just consisted of an interview of what he wanted to major in and what were his interest.
Personally, I think that most of the scholarship weekends are more of a sales pitch than anything else. There are scholarships to be won, but they also want to wine and dine you and convince you to come to their school.
Anyways, congrats to your child. It's very exciting.