USUALLY it's at a showground or similar.
To give you an idea on the '09 Nats

We arrived Thursday, got settled and had a meet and greet.
Friday met some more and watched vans arrive and have a bit more of a chat.
Saturday we had a destination to go to and it was a Water theme park. This is where the big cruise happened. On the way back there were some vans that got a pic taken for Street Machine (VERY happy with this bit).Also had the formal dinner and the Theme for the night's entertainment, and had some beveridge's into the early hours.
Sunday had the public showing with awards afterwards and auction later.(With a few more beveridges.
Monday was to say goodbye's and pack up to go home.

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Skid - I can show you the footage of the 09 Nats later on in the year if you wish.