There's also "Voi" in the city..http://voi.com.au/ It is a bit like a more conventional retail version of Azzaro
I know some here don't rate it - and it certainly is a bit hit and miss. Don't be put off by the Versace satin disco pants. It is certainly worth a look. They stock some Brunello Cucinelli (including shoes), Luciano Barbera. I haven't been in for a while, but I have bought Ballantyne cashmere there in the past. If you are looking for efficienct time use - the city MJBale Store and Harrolds are across the road from Voi in the Centrepoint/Westfield (which is basically an almost sick-inducing temple to materialism, but also quite fun for a bit of a look, if you know what I mean) - the food court and some of the restaurants in there are pretty good and they have GAP, Zara, RM Williams, Bottega Venta, Rhodes and Beckett.
The bottom floor of Westfield is more yoof-oriented - my daughters like it. As well as the mass-trash brands, they also have your quirky japanese T-shirts, trainers, juice bars etc. They have a kind transient 'market place' zome for upcoming local designers - so lots of small-run ladies gear. If you are travelling with a Ms Pink-Socks she might like it.
The Queen Victoria Building has a lot of big name brands - probably not much of interest to the likes of is - but it does have the Ralph Lauren store and a small Herringbone store. But the building itself is magnificent. There are some nice coffe shop/casual eating places to hang out in on the upper floors. Bacco is probably the best of them. CVB also has a fantastic (if somewhat expensive) pen shop. I like to browse in the Antique Print Room. If you are looking for gifts there is also an outpost of the NY Met Museum of Art store on the top floor.
Opposite the QVB in George St is Galleries Victoria - which is basically a smaller version of Westfied in which the leasing department is run by hipsters. So you will find Incu, Carhartt, SUperdry...more Japanese T shirts etc. The food courts is excelent for a quick lunch stop. It has what I think is Sydney's best bookstore - kinokuniya - and the Japanese noodle place just near it is very good.
Do you like coffee? Go to Mecca near the corner of King and York Streets or Klink (281 Clarence - inside the Gaffa Gallery, which is worth a look as well).
Do you like random urban wandering? Walk through the Rocks (which is beautiful but pretty much prostituted to the tourist dollar) through to the Western side of the Harbour bridge (Millers Point) for streets lind with Georgian and Victorian architecture with glimpses of the Harbour and, along the shore, early 20th century wharf buildings. There is Fratelli down there and a number of places to eat. Or you could catch a ferry from Circular Quay or Darling Harbour across to Balmain. As a resident I'm a little biased, but I think it is one of the most intersting built landscapes in Australia, with its mix of sandstone buildings, workers cottages and the odd mansion here and there.
I hope you have a good time.
Excellent Sydney write-up