Aussie train experiences.

Peter mentioned in a reply to an earlier post;

"...I will add the Australian Road trains. I will be on retirement in less then a year and have many plans of things to do. Among them, take the famous train stretch between East and West Australia were the train goes for some 500 km without a curve..."

The train he refers to is the Indian-Pacific which goes coast to coast, east-west across the bottom end of Australia. The straight stretch he refers to is near Cook, South Australia and it is 478 km. More Specific information here and here.
(BTW I have heard that while you can just get seats, a room is very advisable. The journey takes ~3days and the creature comforts afforded by your own room make the difference between it being a chore and a good experience).
Those interested in the Indian-Pacific might also be interested in 'the Ghan' (so named after the Afghan camel drivers who helped open up 'the outback' desert areas - camels being the only workable transport option back in the 1800s - the 'Overland Telegraph' line couldn't have been built otherwise). More info on the train here.
The rail journey that appeals to me would have to be Canada. (If for no other reason that the Canadian countryside is such a stark contrast to the Australian countryside).