Artie my self and a few friends have keys to the Western Sewerage Treatment Plant in Victoria near Melbourne , which is a haven for many types of Raptors and a myriad of waders, bush birds, terns, Stilts, Pelicans, Ducks and is very suitable for longer lenses though once the Raptors spot you you will need to drop back to your 300mm's as they will fill the frame of those and on many occasions I have had to drop down to 135F2 or 700-200mm's.
We also have many wetlands
Artie,
I would suggest in Sydney dropping into the Royal NP, you've got the Hacking river with waterbirds, tame sulphur crested cockatoos, kookaburras and various ducks. You have gallery rainforest lining the river and a stones throw away drier eucalypt forest. Also some of the most accessible azure kingfishers around. You get a mix of rainforest and bush birds down there, so quite close together you may find yellow throated scrubrwen, eastern yellow robin, rufous whistler, cormorants, ducks etc.
You will want to visit on a weekday morning if you can, it can get very busy with picnicers on weekends. It's basically my backyard, so drop me an email if you want more specific information.
regards,
Chris Ross
http://www.aus-natural.com