Evaluating feedback

We all know the score: you attend a conference, business event, or training workshop, and at the end of the day you get a little form asking you to evaluate your experience. You can rate the speakers, venue, lunch and parking on a scale from one-to-five, and tick to say whether you would recommend the event to a friend or colleague. But what about the other part of the evaluation: the open comments box? What was your favourite part of the day?