I would endorse Undarra Lava Tubes too, as well as the Atherton Tablelands. We did a one day each tr

Thanks, everyone. I've emailed the rental company and hope to get a specific answer. Speaking of the road to Chillagoe, is it reasonable to think that we could go there and back in one day from Cairns? My son has just informed me that we cannot go to Australia without seeing the Outback, and I think that's as close as we're going to get. Unless you guys have a better idea!
Why not hire a 4WD and take the back road from there to Undara. The road is not too taxing for those without experience and the new experience will be a lasting memory. Then you will have really been out back. Undara has a wealth of wildlife as well as the largest and longest lava tubes on earth.
The unsealed portion of the road to Chillagoe is pretty good I rode it some years ago on a bicycle, at night. Hard pedalling, but otherwise OK. I think that there was about 10km of unsealed road, and the marble quarry was quite spooky in the dark, white monoliths.
Undarra is really worth a visit. I was expecting the lava tubes to be like a rabbit burrow and was amazed james taylor tour dates to find caves big enough to drive a small truck down. The caves are a micro-environment, and you can walk into some of the caves for about 500 metres. A whole ecology bats, albino insects that eat the bat droppings, and unique james taylor tour dates parasites that live on the insects.
I would endorse Undarra Lava Tubes too, as well as the Atherton Tablelands. We did a one day each trip with a tour company some years ago, and it was amazing. If you drive yourself you'll be able to concentrate on what you are more interested in.