I'm not sure I'd want my passenger car to become a block party. Do Russian trains not have observation cars where people can mix when they want while still having the option for a break when they prefer to be left alone?
Not familiar with the term 'block party' but party in almost any form wasn't how it was.
Full of life meant people stood in corridors, chatted, told jokes, shared food, were polite, discussed stuff. Russians are more reserved than most Europeans or Americans until they decide you are one of them... If there was ever a hint of rowdiness hinted at the car attendant in all the cars soon put a stop to that, usually with a quiet word and then with authority if Vodka drinking had started too early.
During the evenings most remained in their compartments or ate or sat in the dinning car, that was louder than the sleeper cars. There is no observation lounge that we were aware of, it's a commuter train.
The two alternative ultra long distance trains to Mongolia and China carry many more tourists, perhaps they have observation cars but haven't used those as yet to be able to say.
Sometimes compartments were a little louder than the corridor, but that didn't stop the petit female car attendant having a word with a group of 4 officers who were grizzly bear size and had had a drink or two during the day.
Overall more corridor life than the average Amtrak sleeper and a light buzz of sound for most of the day.
I think that if you need a qiete space it would be best to travel 1st class, the problem is you wouldn't have a lot of contact with the people of the country you were visiting.
Just a thought. As that journey is very long most people step onto the platform on the longer stops. Bearing in mind this was February and more than half of the Vladivostok route is through Siberia, so mass evacuation of the train was restricted to daylight and bright weather.
It was interesting as on the long stops the maintainance crew would make rerpairs to water pipes and such like, the car attendants would chip large blocks of ice off of the car suspension, they had specially designed shovels for that, and there was a sort of party atmosphere, genteel maybe but a sort of celebration. It was also where you could buy platform food from the babushkas and the occassional kiosk, it always tasted delicious BTW.
People excercised too in all sorts of ways, and the station buildings were like nothing we had ever seen, lots going on.