Thornton Park at East Balmain is a prime position to view the NYE fireworks, on every other day of the year, its a prime location for a picnic with a view.
Right on the waters edge, theres plenty of grassland with views of Sydney Harbour, the Harbour Bridge as well as Luna Park.
Not only does this park have a top view, it also has access to a ferry terminal if you want to do some on water sight seeing, as well as play equipment for the kids.