So.... What *does* it cost (approximately) to go from Moscow to Beijing, in relative comfort? Say, 2 people in a cabin with private sleeping accommodations and en suite facilities. (Does this exist?) How much more expensive does it get to take it all the way from London to HK?

By the time I seriously consider doing this, I'm not going to want to do the backpacker route which I loved so much all over Europe when I was 20. It'll be my wife and I at age 60 and we'll want, y'know, a real bed and a shower. I truly have no concept of what this costs, other than I don't expect it to be either $400 or $20,000.