If you go into a restaurant that seats 250 people and there are 100 people dining, the place looks empty and you tend to wonder if the place is any good, if they can't fill the place.
But if you go into a restaurant that seats 90 people and there are 10 people in line waiting to be seated, then you think, "hey this place must be pretty good...look at the people waiting to get in".
From what I remember people talking about at the last few years of conventions is that there was ample room for everyone. Which on one level is fine. Plenty of parking, plenty of seats. No need to rush to save seats, no need to worry about parking. But OTOH, if it's planned so well that convention halls and coliseums appeared less than capacity it could send the subliminal message that there must be a reason why the WTS can't fill this place anymore. So, lesson learned. Create the illusion of a "sell-out". Create that sense of needing to get there early. Better to have people storming to save seats than to aimlessly wander in a couple hours late (if at all).
Just a thought...