Obviously depends on the user. When I was younger I tried the night train thing on a trip that hopped a few European cities. So, stay in Munich for 2 nights, then on the 3rd night, get on the train to Vienna. Stay in Vienna for 2 nights and get on another train ...

Basically spending 2 out of 3 nights in hotels due to the night train (compared to if we'd done the same itinerary but with daytime trains).