Where to go next before we sell our touring 4WD?

We bought a 2002 Landcruiser Diesel Turbo fully decked out as a touring 4WD for our 3 month trip to the Kimberley this year. We also bought an off-road camper trailer that we intend to keep.

Now we have time for another 3 month trip (start of September - end of November) but I'm not sure where we should go. I want to make use of the 4WD before we get rid of it.

Although we are a young family (with 2 small kids) we have the equipment and supplies to survive 2 weeks without restocking.

Our last trip was:

Brisbane -> Alice Springs (via Charleville and Mt Isa)
Expore all places around Alice Springs (incl. Uluru, Kings Canyon)
Alice Springs -> Kimberley (via Tanami Track)
Explore all places around Kimberley, south as far as Broome, then up Gibb River Road and Mitchell Plateau.
Kimberley -> Darwn (via main highways)
Darwin -> Mackay (via main highways)
Mackay -> Brisbane (via main highways)

Any suggestions are welcome!

We were thinking of going south (we live in Brisbane), or through the Birdsville track, but wondering if we should get up to Cape York or not?