If you want to carry back more than souvenirs and stuff from exhibitors, plan ahead to make the most of all the informal and unstructured moments, "the meetings in the hallway." You make them happen when you introduce yourself to someone sitting near you before the keynoter begins to speak, when you strike up a conversation with someone in the hotel lobby or at a luncheon, when you welcome a newcomer, or when you congratulate a new board member at the opening reception.
The hotel can be awful, the weather can be lousy, the speakers can be mediocre, but if you meet just one person who can help you boost your sales, advance your career, land a new job, or solve a problem that's festering back on your desk, you'll call the convention a success.