large size 3D TV

Presumably you will need a lot of glasses and a wide viewing angle that covers all those in attendance. Hence, Samsung and Panasonic are out and the most suitable for your purposes will be 55LM6700. This top the line machine is fully loaded with features, magic motion remote control and the glasses are cheaper as they use inexpensive technology. We have been using the same model at our pub and it is a big hit with the visitors.

Why do you want to use a 3D Tv for the convention center..As per me going for LCD will be a far better option...

A 3D projector would be a better option

Please be precise with your budget and screen size so that you can get suggestions accordingly