Visiting Brown often won’t do anything. They don’t track visits because often # of visits is more closely related to finances and distance from the school than it is from interest.
If your school’s GC has a relationship with the school and his/her word means something to them, their saying it’s your top choice is a way to communicate it. Otherwise there isn’t really anything because as previously stated, there’s nothing stopping you from doing/saying the same thing to every school you apply to.