The train is great, and very convenient, taking you from city center to city center. We took a night train, and slept most of the time; the night trains take most of the night so its morning when you arrive. There are lots of trains, day and night, some a lot faster than others; and many posts about train travel on this site; so search "russian train" or something similar on the Russia forum, see what comes up. Then if you still have questions, ask again.
The views we saw (when we were awake) were interesting-- not spectacular scenery though as it is flat-- forest and farmland.
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Friendships that have stood the test of time and change are surely best.