I think you're kind of getting the wrong idea.. It's not really a meet up exactly.. I'll try and explain it..
George street is pretty much the main street in the city for night life.. Well the longest anyway.. Clubs and pubs etc are on this street, lots of people walking up and down, girls etc.. Everyone is just driving down around up and down there showing off their cars or trying to pick up or selling drugs or checking out the other cars.
If you follow george street all the way to the end, you will come to 'The Rocks' ( ask for directions if you get lost ) Quite a few people will be parked around there from 9-11pm having a chat etc with their cars. They might get told to move on later because, they made it a no standing zone after 11pm I think.
So.. George street is like the catwalk.. and 'The Rocks' is like the semi meet up have a stop and a chat spot.
EDIT: I just realised.. There's actually a SAU skyline cruise tonight.. starting at Liverpool. If you check the NSW section under events you will find all the info.. there might be 30+ cars going. I'm sure no one would have a problem taking you.