We have just got back from a short break to Broken Hill, which is just over 500 km NE of Adelaide. I've been there before but this was the first time with kids in tow. We had a great time, the kids loved it. There is loads to do, lots of accommodation (we stayed in an old miner's cottage) lots of interesting museums and loads of art galleries. You drive for miles and miles in the middle of nowhere and suddenly there is a town of 20,000 people, right in the middle of the desert.
The highlight was going down the Daydream Mine near Silverton - makes you realise how hard life was in the 19th century, it was mined by Cornish miners who walked all the way from Burra to Broken Hill in search of work - see http://www.silverton.org.au/ddream.htm.
At Silverton there is the Mad Max Musuem which is run by a family from Bradford - see http://www.silverton.org.au/madmaxmuseum.html
If you want to see outback Australia then Broken Hill is a great place to visit with an interesting history. Very friendly people too.