Sydney
From GeoWiki
CBD Area
There is a high density of caches in the Sydney CBD area with the normal distribution of fabulously located caches and bad-reception difficult caches. Lack of parking and traffic congestion often make it best to get around on foot.
There's a good map here that you can use to help with your planning.
Around the harbour
Sydney Harbour is probably the most famous attraction of this city so it makes sense to focus your travels on some of the fabulous caches that have been placed around the water.