The 'premium' tickets to the galas at Roy Thomson Hall only allow you to sit in the upper balcony, so don't expect to see anybody up close. If you want to see George Clooney up close, you should go early and stake out a good spot near the red carpet. The stars will usually arrive 30 minutes before the start of the screening (but you should be there much earlier). They'll do interviews (E-talk, Entertainment Tonight, etc.), pose for photos, and usually sign some autographs. Some stars spend more time with the fans than others. Their publicist will keep dragging them away to do interviews with the press.
They're changing the red carpet at RTH this year, supposedly making the walk longer. This could be good for the fans, as you may have a better chance to see. I happened to be near RTH last year when Brad Pitt arrived and you could hear the screams a block away (literally, I heard the screams from Adelaide and Simcoe). It was a mob scene outside RTH.