- Oblivion's character creation system
Have you ever taken a look at the character creation system in Darklands? As the game is abandonware, you should be able to download it easily enough. I've never seen anything as good for giving your character, not just a selection of skills, but fusing them to a fictional background, anchoring the figure you've created in time and place.
Civ4's exploration and empire management system
What I think I liked best about Civ4 was its diplomatic feedback system, explaining exactly what was affecting the reaction of an AI to you, positively and negatively, and by how much. Hope you include that.
- Capitalism2's production system
Have you taken a look at what Ascaron did with production and economics in Patrician III and Port Royale II? Definitely worth a look. It's extremely detailed and almost certainly beyond what you want to offer to your audience, but there could be ideas in it you find effective, and easily implemented.
- Wizardy 8's quest designs and character dialog system
Never much cared for the Wizardry dialog system: far too much hit and miss, plenty of frustration from word trials that brought up nothing. What about the kind of thing done in NWN2 (and the forthcoming Age of Decadence), where you get a dialog tree with extra branches if your character has certain skills, or done certain quests, or hit certain achievements?
I'd also like to suggest adding a conversation category for "gossip" between mage rulers. Freebies, offered gratis about another of your peers, that may be accurate, partially accurate, or completely inaccurate--and could be well meant, depending on your relationship with the AI, and/or an attempt to sow discord or manipulate you into making a decision they want.
Just some thoughts. This really sounds excellent, so far. Best of luck with it!