Looked through the NSW's website on public transportation, there are a number of options for unlimited access. The most comprehensive option is the SydneyPass, which costs $170 for 7 days including RT AirportLink. However, I also found the Red Travelpass covers a lot of ground (& water) within central Sydney, but only costs $38 for 7 days. I realize the Red Travelpass doesn't cover the Sydney nor the Bondi Explorer, but if I figure the regular system would get me to those places, too. Hence, is it worth paying extra to get the SydneyPass?
Depends on where you want to go in Sydney - the travelpasses are mainly designed for commuters, but can be useful for tourists as well. Whilst you can use the travelpass to get to where the red and blue explorer buses take you, you might have to use convulted routings to get between attractions. You will also miss out on the commentary and, particularly during the peak periods, have to put up with crowded buses.
One tip with the travelpass - if you purchase it after 3pm, the rest of that day won't count as part of the seven days, so you will end up with a bit more travel than you paid for.
Dave