I've taken the train from NY to California! It was a great trip! I imagine the Trans Siberian Train would be beautiful. Can't give you a hands-on account of your plans, but from coast to coast in the United States on AmTrak was awesome. I wouldn't recommend it for those looking for 'posh' accomodations as our train took us through bumpy cargo stations and frieght yards and the view sometimes looked like Thomas the Tank Engine gone bad, but it was an adventure, just the same and a wonderful experience as we got a first-hand account of how humongous and beautiful our country really is. My husband and I got a little room with bunk beds that folded out and were very comfy at night and had privacy and played cards and read during the day. There were special cars that were for sightseeing through the Rocky Mountains and the dining car was...interesting...but the food was really way better than we expected. And the staff was very friendly and accomodating.
Hope you have a great trip!! Let us know how it goes and post lots of pictures!! I'm posting some pics of my trip...one is of our train, the Southwest Chief, parked in Albuquerque, New Mexico and the view of Albuquerque from our room on the train. Another picture from our window of the cool mountains in New Mexico and one of my hubby and I in California (if you look close, you can see the Hollywood sign behind us). And a sideways picture of the Sears Tower in Chicago outside the train station. What a blast we had. I real treat to see the countryside like that...I'd LOVE to take the train you're taking. Have a blast!!