Originally Posted by
CPMaverick
I third the Park Hyatt if you want to go to the Opera House, can't be beat.
In general if I have an overnight layover in SYD and don't want to be in tourist-central, I like the Crowne Plaza Coogee Beach. A quick taxi ride and a quite relaxing area. The hotel won't wow you, but it is a solid property right on the ocean and has a 24 hour pool and gym. The walk from there to Wylie's Baths (ocean pool) is very nice too.
You could probably toss the IC in Double Bay in there as not being in tourist central. Although then you have to deal with every spiv in Sydney.