I've never been to the Host Club panel/tea party, but I think hosting the masquerade would be a great idea. I was really looking forward to the masquerade, but I think if the Host Club leads it, it could have a much more masquerade feel than what I've heard the official masquerades have been like. If you sold tickets and provided cheap, simple masks for people who don't have them, it could be quite fantastic.
On the Masquerade thread, someone suggested having a group of people who know at least the basics of dancing go around the room and dance with people so they can teach them the basics as well. I would be a big fan of this, because I have absolutely no dancing experience, and I think it would be a perfect role for the Host Club members to fill. : D
My apologies if any of these suggestions are not-applicable because of my inexperience of having never been to the Host Club panel or the Kcon Masquerade. : x