Tetsuyas is one of my favourites - great degustation menu and the location is a nice sanctuary of japanese gardens in the middle of the city.

Aria down near the Opera House is great too - ate there last night and again enjoyed the 7-course tasting menu. If you go with the matched wines beware that the food-to-wine ratio is stacked in the liquids favour - so be prepared not to drive home.

The revolving Summit restaurant at the top of the tower in Australia Square is quite nice too - the food isn't in Tetsuyas league but the view is spectacular.