Things I'd like in Skyrim;
Polearm weapon tree with spears, halberds and javelins. Spears and halberd would be two handed, javelins one handed with shield.
Expanded factions with;
New story and radiant quests
More faction armor
Faction perk trees
Expanded Civil War story;
Replace 'leader' of your side by reaching Tullius' rank or overthrowing Ulfric Stormcloak (For Stormcloaks you also get to choose a new faction name).
Lead your faction in war against Thalmor by raising and leveling up an army, and creating alliances with other nations like Hammerfell.
Allow your chosen Civil War faction to remake a new Empire, starting it in Skyrim like the old one.
Expanded Thane and Jarl system;
More quests and rewards as Thane.
Pick one city to become Jarl of through story quests.
As Jarl, grow and develop your Hold and army.
Jarl perk tree
Blades;
Allow special quest to get Blades to ally with P (you know who, don't want to spoil it)
Create new order of Blades that allies itself with P and those like him
This new order would hunt evil dragons and new dragon cults.
More types of dragons
More creatures like minotaurs, sea serpents, and kraken (mentioned)
New factions
New armor, weapons, and spells
Perhaps new areas to explore, like islands to the north (as in Morrowind)
… I think I'll come up with more
