Backstories allow me more fun. Laetra's character is a half-elf with a disdain for elves and magic (more or less) so I have some fun social things to do when the party rolls into town.
I debated doing two games at once in the same world. The big idea was to pit them against each other, on different sides of the battlefield. It could almost be played like an MMO of sorts, if one team takes a field, their side gets a bonus to food production, or claim a mine to get more iron and more soldiers. After every play, the parties would spend any extra time (like, 1 month) in town to let them do crafting checks, earn spare gold, and let their faction move resources, refill soldiers, fortify positions, or make attacks. The only real limiter, would be that the two parties couldn't be on the same field at the same time, like one team assault a base while another team defends, because the groups would be scheduled at different times, and everyone knows that each player would be taking lethal shots at the others unfairly.
Could be fun, could result in a lot of grind recapturing the same areas again and again. And I'd want a lot of extra time to set up a large playing field, if we were going to go all out with this. And I'd have to figure out a way to balance things. After all, for the most part it'd just be one team claiming a territory each week, since the players are so much stronger than average NPC then any siege that's aided by the party would overpower the enemy. So, I'm not totally sure how to do things... There's always the option to let me (the DM) play as my own party and make player-equivalent NPCs to throw super-spells around and stuff.
In fact, Pathfinder includes rules for this. Kingmaker campaign has rules for taking cities, fielding armies, and large-scale payment, but I haven't been able to get a legal free copy, so I didn't look into it very deeply.