You'd probably save yourself some airfare, face, and stress by arranging a visit on a different weekend entirely. Let the admissions people know you're coming and they'll make sure you get a tour, sit in on a class, etc. especially because you're already an admitted student. You won't get to hobnob/get drunk with with your future classmates, but HLS also won't have control over your agenda and you won't get as much blatant PR (not that Harvard needs to do much convincing! P.S.: Please accept me!) Go on a weekend that's comfortable for you.
I don't know, I thought HLS's admit weekend last year was really great. All the faculty are there, available, all the student orgs are there and ready to talk - you really get a vibe for the excitement of the school. Yeah, there's PR of course, but I think it was really worthwhile for me last year. Just my two cents