There has been a bit of press about the Greater Sydney BikeTrail lately including this post from Bicycle NSW. The trail is over 200km in its classic sightseeing route and can be trimmed to 150km and you can still catch most of the highlights.
To whet your appetitie, check out the slideshow of 220 km trail or you can read about the trail and see maps here >>
You can see more videos of the trail here including the lockdown relay
Note: A path from Cronulla to Sutherland is now on the Sydney Map. Quite a climb, a few 100m of footpaths but pretty decent really.