Party Coach
Friday night trains should have a party coach.
On the overnight ski train that we went to Tignes on there was a party coach that had no seats, a small bar and some music and subtle lighting. The benifit of this is that if you want to party you can head on down to the disco but if you want to sleep you can. I think that all trains in the UK should have this on Friday nights as this would move the large groups of people who are off for a weekend of parties into their own area and keep the rest of the train a little less busy for those who want to sit in peace.
Sort of the opposite of the quiet coach.