When I lived in Sydney, i quite enjoyed Jamberoo. Bit of a drive, but its only about 90 minutes for the average Sydneysider. You can spend that long getting from the western suburbs to the beach on a bad day. Generally you made a day of it, but you could take in pretty much whatever you wanted and set up camp for the day. Prices were reasonable IMO.
I live 45 mins - 1 hour from the gold coast parks and have only been to Movie World once for a private function, which was cool. Maybe when the kids are older I'll get one of those annual pass thingys.