Journey Beyond have designed a pair of packages which go out from Adelaide and return in one week, allowing it to repeat the next week with broadly the same set of rolling stock. Further to that, they've designed the schedule to do the boring bits overnight.
To add anything means either taking something away, or lengthening the schedule and shuffling things around.
It's clearly aimed primarily at international visitors, so 'natural' attractions such as the Grampians or 12 Apostles are clearly going to take priority over ex-mining towns which can be found locally in many of the countries which are the targeted markets. The only one I can't work out is Canberra - it will be interesting to see how they run that tour.