I'm not presenting. I'm just going. I'm meeting a few people for faculty position interviews and going to take some courses.
In my experience, the dress is really varied at these things. I'd say about half of the people are sport coat and slacks kind of people. Presenters are almost always in suits. The rest are polos and khakis kind of people. I mean, if you're going to be sitting around all day and taking courses or reading posters and stuffing your faces with food, then you might as well be comfortable.