We have stayed twice at the Southern Cross Sydney & Towers on Goulburn St. $80AU including tax.
It was a great deal, so we stay there every time we go back. Ask for Rm 820. LARGE corner room with bedroom, large bath, living room and dining room.

We thought the location was fine. Before discovering Southern Cross, we stayed at the Sheraton Four Points (Darling Harbor). Nicer hotel, think it was $150 or $175AU. Great service, and of course right on the Harbor. Just depends on what you like.