We did the Silver Star once as a family but tail-ender me cannot remember anything other than standing in the corridor looking in the doorway of the sleeping compartment. Did an overnight from Istanbul to Ankara in the mid 90's though; recommend.

I travelled London to Istanbul via Amsterdam by multiple trains in July/August. It was fantastic. Every time somebody asked me why I didn't fly I told them about the (lack of) passenger railway options in Aotearoa.