There are a number of possible rail journeys in Australia, not just the long distance trains. I would recommend taking some suburban trips in Sydney, Brisbane or Melbourne, or even Perth (Western Australia) if you get that far.
Remember, Australia is about the same size as the continental USA, but with a much smaller population, so long distance trains are not frequent and take a long time to cross the country.
Here is the GSR Link for the Indian Pacific and Ghan
http://www.gsr.com.au/
The Queensland Rail page also gives details of other services. The Queenslander and Sunlander run up the Pacific coast from Brisbane to Cairns and these trains have similar facilities to the Indian Pacific. If in Cairns, a trip up the Kuranda Range line is worthwhile.
http://www.traveltrain.com.au/2/default.asp
The Countrylink system based in Sydney (NSW) provides day services to many destinations, with some limited sleeping berths for long night journeys. The sleeping compartments can be reserved for day journeys at normal first class fare.
http://www.countrylink.info/
Sydney has a very extensive commuter network extending more than 100 miles out, including many scenic attractions.
http://www.cityrail.nsw.gov.au/
Around Melbourne (Victoria) a similar service is provided by Connex for shorter journeys and by V/Line for longer journeys.
http://www.vline.com.au/index.aspx?sid=0
It is worth checking these sites, and the maps, in conjunction with a tourist guide so that you can combine train rides with the best scenery.
From Sydney, a trip to Kiama, on the coast south of Sydney, provides truly spectacular scenery with the train running close to the coast at many locations. A trip north to Newcastle runs along some in