would anyone know if the c4 couchette berths are wide enough to fit a on-the-heavier-side mom with her 18-month old kid?
Also, are the double sleeper berths much wider?
We plan to travel from Rome to Zurich .. so it is a long journey, and I don't really want to completely miss my sleep!
I can't answer your question on the the sleeper. However, have you seen the special fares for this run? CLICK HERE to see the special fares. The 314 Luna train leaves at 19:58 and arrives in Zurich at 8:34am. It's a 12.5hr journey. I'm not sure if your ready to sleep at 8:00pm. For sleep, many people can and love it. Conversely, many people have difficulty sleeping on a night train.
You might also look into a flight from Rome-FCO to Zurich-ZRH on an inexpensive airline. www.airberlin.com makes this flight. You would change planes in Hamburg or other location but fares are as low as 49Euro if you book early. It's a 4.0hr journey. There is a child's fare as well.
You may be required to book a separate berth for an 18-month-old. However, if this not required and your child is comfortable sleeping on the floor, you could book a one-bed sleeper for the two of you.
The couchettes on this train are barely wider than a hospital gurney. See photo from the Swiss rail network at http://mct.sbb.ch/mct/en/euronight_vierer.jpg