The Hawkesbury river area of NSW is a hidden gem. I spent a long weekend there in January with friends who live in the river. To waken up in the morning and all you hear is birds and water skiers as they ski the river. It is a very peaceful area where you could rent a boat, cottage or there are campsites. Windsor is the nearest town and it has lots of small shops and coffee docks.
It’s in the way from Sydney to the blue mountains but by a back route not the normal tourist trail. There is a good train service from Sydney central if you don’t have a car.