Hi,
We will be taking the train from Rome to Venice. Is there a better side?

To avoid any confusion, while standing facing to the front of the train, left side is left. (excuse me if this sounds like a stupid comment : )

Thanks again for your comments.

If you or anyone can figure out a way to determine before the train arrives which seats are on which side, congratulations. So if making a reservation, it is a total crap shoot.
But if you're looking for which side to sit on without reservations, well, I don't think it makes much difference except that you may be sitting more in the sun in the morning on the right, and more in the sun on the left in the afternoon. View wise? Toss-up. Pretty things on both side.

If you're into "speed" then sit on the right-hand side so you can watch as the train breezes along faster than all those drivers on the Autostrada. Once you enter the 11-mile long Appenine Tunnel the side you're on won't make any difference.