The most luxurious night trains operating as a scheduled service (instead of as a rail cruise like the Venice Simplon Orient Express) are the Russian connections Paris-Berlin-Moscow and Nice-Vienna-Moscow (and Berlin-Moscow).
If you want to know how modern travelling should be – take a look at this video:
https://www.youtube.com/watch?v=L1HXZ8_8pAk&feature=youtu.be