United Frequent Flyer miles... best use for Europe (?) travel in May?

Hello again travel advisers :wink: I’ve been over on my Munich thread, but this weekend I hope to book the Venice-Munich overnight train (we are within 3 month window now). Travel will be 9pm-6am.

Family of 4 - couchette or sleeper? The couchette compartment looks adequate, but I am thinking of going for the more expensive / more comfortable sleeper (400 euro total for 4, not too terrible for transportation and lodging).