Just taking a break - my PS3 is thinking of trying to start a union since Dawnguard came out- to post a few wish list idea's for DLC's I think would be awesome.
1. Invade Sommerset isles. With High King Ulfric at the helm. ( Substitute random legion dog who got tired of looking Thalmor boots if player sided with Imperials )
2. Hircines Hunting grounds- Hiricne would lead the hounds and Boethiah would lead the Hares faction, to settle an age old dispute between them.
3. A DLC that lets you pick NPC's to train in all aspects of combat or magic that you've mastered. This NPC would wear the armor you supply, use the weapons you give and fight in the style you selct, then follow you into battle and learn first hand... getting stronger until they receive some sort of title from a neighboring kingdom. Then they become "Epic" quest givers, where they join as "Thane so and so" and are essential for the duration of that quest. Eventually what would emerge is the new power structure of Skyrim itself.
4. An evolution of pre existing NPC's and your relatiionship with them.... if you've gone on X amount of quests with someone, some kind of battle bond being in effect when your fighting alongside them. Lets say your married to your follower, it might be "Lovers Zeal" where the NPC gets an enormous attack boost if the player characters health drops under a certain percentage.
Dawnguard calls... so I'm off.
PS- Idea 2 is an old one but I have a full fledged campaign and details written out that I'd be willing to share if anyones interested.