Jeanette_Isabelle, while I don’t recommend storing soda, if I were going to do so I’d be looking at either 20oz or 2L plastic bottles. It is my impression that if kept in a cool, dry, more-dark-than-not space that they’ll last for some years. While I’ve seen (and even consumed) can of soda that were 20 years or more past their “sell-by” date, the contents had suffered more than what I would expect from an intact plastic bottle.

Glass bottles, as mentioned above, are in some respects the best option. As you know they’re expensive, bulky, and awful to clean up in the event of breakage.