Check out my signature for my pirate pack idea!
I wouldn't necessarily want a story pack that has a linear storyline. If you've played it once, you've seen it all. That's boring. I would, however, like more packs that otherwise wouldn't fit into a "realistic" theme (ex. Seasons, Generations etc).
These packs are kind of like mini-games within the game for when you want to mix things up, but it stays contained within that world so you don't have to worry about weird themes taking over your "normal" saves.
Post-Apocalypse would be very fun and a challenging, different-every-time "story" to play out. There would be certain story elements, like pre-made factions, ways to create a good or bad "new world," radioactive llamas to destroy/cure etc, but you'd still have the freedom to simply enjoy playing in that world in whatever way tickles your fancy.
I'd also love a Castaway theme, as it would add a lot of fun survival gameplay that can be carried over to any other survival or historic save I can think of. Also, who doesn't want to create their own society on a shipwrecked island?
