Hi Keith,
Which way are you planning to go? Longreach isn't exactly "as the crow flies" to Cairns.
The Kidman way is a good drive, with some interesting towns along the way. Take care with wildlife.
Just north of Bourke.......
http://www.backobourke.com.au/exhibition-centre.phpNot big, but something to look at. A reason to stop....
If you're going to be around Longreach, Barcaldine has.....
http://www.australianworkersheritagecentre.com.au/ http://en.wikipedia.org/wiki/Tree_of_Knowledge_(Australia) .....not much of it left now, though....
We found both interesting for the history.
Depending on your route, you could have a look at Carnarvon National Park. Excellent scenery. Very nice for a few nights' stopover. No free camping, but Takaraka has good facilities. It's a fair drive off the highway. Check prices before pulling in.
Expedition National Park is also very nice. Good scenery, with camping (small fee, envelopes). No facilities where we camped, but may be available in other camp spots. It's just across the highway from Carnarvon NP.
About 20km north of Charters Towers there's a big free camp area. It's in Camps 6. Be aware, it's well used and has been very busy whenever we've travelled through there. We've found it better to go on to Greenvale. A nice little place to stop (pub
).
Undara Volcanic NP is also worth a look if you're interested in that sort of thing. We enjoyed it, but check all prices before pulling in.....