AdCom Events: will they even remember me?

^^^ Agreed.

The value of going to an info session or visiting a campus isn't the one in a million chance that someone from adcom will remember meeting you when your application comes up in the pile. The value comes in getting firsthand information from adcom, alums, and current students about what their school has to offer and how it has helped them reach their career goals...and if you're able to talk to students offline over a beer you can also usually hear stuff that doesn't fit the party line, such as their gripes about their program or what they like and dislike about it compared to other schools.

Even if the school has fairly minimal representation at the event, it's still easy enough to talk to a student there, get his/her email address, then follow up a week later with an email along the lines of "I know you said you're a former I-banker who wants to go into private equity, but do you have any friends who would be willing to talk to me about their internship experience/job offer/club activities in entrepreneurship and social enterprise?" That's a good way to get more firsthand information, plus if you find that students aren't particularly helpful then that fact may raise a bit of a red flag about the culture of the school.