My Idea's, after over 300 hours in oblivion, and 200 hours in Skyrim (didn't even get halfway through I feel either), would be.
-More furnishing options for your homes. IE. the useless basemant room in solitudes home, waste with unusable barrels and a floor mat.-A fortress/tower type home like frostcrag spire in Oblivion, but bigger and better
-More Weapons, Crafting materials, and enchantments-New Perk Tree's!!! I love the ones we have, but how bout some more.
-As for quest lines the suggestion about Becoming Talos or part of Talos like Oblivion did with the Shivering Isles and Sheogorath seems like a great idea.
-Dwarves.
-The ability to travel to morrowind, or other places in games past, even if it's just to visit a market and trade for exotic goods.
-Scimitars in likeness to Drizzt Do' Urden in R.A. Salvatores fine novels ;x PLEASE!!! Icing Death and Twinkle i think they're called.-SPELL CRAFTING! somehow, someway, if this can be done, do it!-New guild/questline-maybe a dweomer ruin as a mansion/home?
-A companion dragon/intertwine with a quest
-more Treasure Maps, with awesome Loot in them.
-xbox360 creation KITIm sure I could fire off more, but this should be enough to get an idea. Cannot wait to see what actually comes to fruition. I know some of these are pipe dreams but I had to plant the seed!