OK folks I have just returned from a sensational weekend at Wollondilly River Station.
Although there were quite a few people around the place was big enough that others didn't really matter that much,
We camped on the western side of the southern part of the river and it is a great place to swim, canoe or fish(as long as you don't mind not catching anything).
Brian the owner is a little tricky to deal with but basically books you in, points you towards a general area to camp and lets you get on with it. (tip: don't try to stroke his dogs as he doesn't like it)
The place is really picturesque and peaceful (when the people across the river turned their music down).
Can't post any photos here (YET) but happy to email them if you send me an email.
This place, I would imagine, gets pretty busy over long weekends but still worth a visit.