Well the obvious must-see things for a tourist would have to be the opera house and the bridge - a bridge climb would be fun if you arent bothered by heights.

I have been to Sydney a few times, but mostly for work so it's been a combination of very nice (and expensive) restaurants, and a heap of room service for me. Pick the accommodation close to the harbour would probably be my advice, but there are heaps of decent accommodation options. As far as places to avoid, I'd say just dont stay right on Kings Cross.

I'd better let some of the locals answer this one if they are on though, they'll have a much better idea than I do