I really enjoyed the overnight train on that route. I was doing it in reverse... Venice to Milan on an afternoon train, then transfer to the overnight train in a private sleeper from there. Maybe it's not for everyone, but we really enjoyed the trip.

I don't know what scenery we might have missed, as we were asleep at the time
;-)

My sister and I also took night trains (with sleeping berths) from Paris to Venice and then Rome to Paris.

If you're traveling in the spring or summer, you'll get just the right amount of scenery (even the most gorgeous scenery can get dull after 8 hours of speeding past it).

I agree with AlanRow, as well... the added perk of not having to worry about my luggage was a huge plus.