Keeping everyone occupied in the car
Long legs are unavoidable on some routes, and the honest answer is that screens help. The useful preparation is downloading everything before you leave a town with coverage, because large parts of every route on this site have none — including sections of the Bruce Highway, most of the Eyre Highway and effectively all of the Gibb River Road.
What works better than screens, when it works, is giving each child something to track. A tally of road-train trailers, a list of town names, a note of every animal seen, or responsibility for the paper map and calling out the next town, all turn a passive drive into something with a job attached. On the long inland roads, the changes in country — from farmland to saltbush to gibber plain — are more visible than people expect once someone is looking for them.
Food is the other lever. Regional Australian towns often have one bakery, closing at two, and nothing else. Carrying enough for a full day means the schedule is set by the driving rather than by finding lunch, which on the inland routes is a real constraint rather than a preference.
Practical details that make a difference
Pack for the overnight temperature rather than the daytime one. Inland Australia in winter, and the highlands in any season, get far colder at night than the daytime forecast suggests — near freezing in the Flinders, the Red Centre and Karijini in June and July. Warm sleeping bags and a proper mat under each child do more for the trip than almost anything else you can carry.
Sun and shade are the daytime equivalent. Hats, long sleeves and a shade tarp or awning matter, and the middle of the day in most of Australia is not walking time. Water is the other constant: carry more than you expect to use, and refill at every town.
Expect no phone coverage for large parts of any trip outside the cities, which means downloading anything you plan to rely on — maps, entertainment, park information — before you leave town. And carry a torch each. Campgrounds have no lighting, and a child with their own torch is a child who is not lost.
Editor's note — Tom Ridley
We stopped trying to do the drive and the destination on the same day, and everything improved. Now the arrival day is deliberately short — two hours of driving, set up by lunch, swim in the afternoon — and the second and third days are the ones with the walks in them. It costs a day per stop and buys back the entire mood of the trip.