On many occasions, in Europe (the Austrian ones are good, the new Swedish ones to Germany are decent), the UK (London-Scotland) and Australia (Sydney to Melbourne and Brisbane; they’re comfortable and good value, though about to be phased out because the management believe that seats are good enough). I can recommend it.
I did a sleeper train in Thailand and it was amazing. During the day it had seats and at some point in the evening a person would come and turn the compartments into bunks. There was food too if I remember.
When doing my military service (sweden) I got rides on SJ’s night trains plenty of times in their six bunk cabins. With five other enlisted. I didn’t mind it but it was Spartan. Simple and serviceable. And you felt the ride. If I had young kids with me I would get a private two or three bunk cabin.
But I still remember waking up in the mornings, leaving the cabin to head out into the corridor to open a window and inhale the fresh northern air.
Yes
I recently took a trip with two children (4, 18 months). We did a sleeper train from Brussels to Prague (EuroSleeper) and from Vienna to Zurich (NightJet operated by OBB)
The OBB trip was phenomenal. Great amenities, and we were on their older model. So I can’t imagine how great the newer carriages are.
The EuroSleeper was awful. Bad amenities, never received our (prepaid) breakfast, temperature was stifling (85° F, 29° C) and the ride was not very smooth.
I would gladly do a sleeper train again, but maybe not with kids so young. Probably not until the kids are 10+