Pro tip: book the 6am bus in Vietnam, not the overnight sleeper, and you'll actually arrive alive
I did the overnight sleeper from Hanoi to Da Nang twice and both times I got maybe 2 hours of sleep thanks to a guy snoring 3 feet from my head and a driver doing 80 on mountain roads. Last month I took the 6am limousine bus instead for about $18 and it was night and day, actual reclining seats, a bathroom, and I rolled into Da Nang at 3pm with energy to work. If you're trying to keep up with client calls while moving countries, don't treat sleep as optional, it wrecks your whole week. Has anyone found a route where the sleeper train actually beats the daytime bus?
I've done both directions of that Hanoi to Da Nang run and honestly the sleeper train can win, but only if you get a soft sleeper in a 4 berth and book the whole cabin or at least get lucky with quiet cabin mates. The big thing the train has over any bus is you can actually stand up and walk around, plus the mountain stretch past Hue is genuinely one of the best views you'll get in the country and you miss all of it on a daytime bus when you're staring at the back of a seat. Where I'll agree with you is the sleeper bus, that thing is a torture device and I don't care how cheap it is. But train beats bus if you plan it right, the mistake is people book the hard sleeper and then wonder why they feel like death.