In 2014, I took my recumbent tricycle to San Francisco, and cycled in the direction of St Louis. I got as far as Tucson in the time I had available, and there boarded a train the rest of the way: something like a hundred dollars (not sleeper), and an extra ten for my trike, considerably cheaper than flying, and more interesting. Good stuff.
In 2021, I returned home from India to Australia once I could, but with quarantine arrangements at the time, had to land in Darwin. I knew there was a train from Darwin to Adelaide, but sadly discovered it’s exclusively targeted at tourists, something like $1,200. So I flew to Melbourne instead, around $450. Disappointing.
Rail is delightful stuff. I live out in western Victoria, and vastly prefer taking the train from Ballarat to Melbourne, rather than driving. It’s often 5–10km from the highway and goes through beautifully picturesque areas, whereas the highway is comparatively boring.
Going slow is also great. I’ve made a few multi-week cycling trips now, in the USA and New Zealand (and single-week in Australia). Take the different way you experience things by rail, and amplify that considerably further, though in slightly different directions as you’re still largely tied to roads. Recumbent tricycles are particularly excellent for the endeavour, with their inherent stability, high capacity and greater comfort. (I use a Greenspeed GT-3: for air/rail conveyance, fold it in half and wrap it up in a tarp which can serve as a ground sheet when camping. Treat the rope you wrap it all up in to be consumable if dealing with the TSA: they’ve destroyed it thoroughly every time (like, longest remaining piece 1.5m out of a 10m rope, they’re putting effort into this), and significantly damaged the tarp a couple of times. Australia and New Zealand have never damaged either.)