well... skyrim has an amazing set, looks like the dwelmer ruins are BACK, and i love them, i don't know why, i never really played attention to them until knowing they would be redone for skyrim, that just gave me hope for better dungeons, since there is MUCH more then loot covering them, im even trying to do an mod remaking dwelmer ruins for oblivion, not taking them from morrowind and adding in oblivion, no, remaking all of it, with better models, and some models and textures used in oblivions dlc, the orrery...
I too am glad to see the return of the Dwemer. I also look forward to seeing the architectural differences between Morrowind and Skyrim, as the Dwemer seem to have integrated a lot of stonework this time around. I think the Orrery in Oblivion was also a nice direction, but sadly it was a very small example.
My personal joy is mainly the animations, like the OP said. I'm a big fan of getting to watch what I do and what others do. I tend to play in first person for the immersion, but for some epic battles I may just switch to third person to watch myself inflict carnage. I've never been able to do that in Morrowind and Oblivion because the animations were so jerky and didn't work well. You swing a sword, you seem to miss a little but still land a blow because of basic attack range, and the opponent does not recoil. The footstep animations were skippy if you tend to dodge around a lot like I do to avoid being hit. One feature I really like when it comes to animations is when they work together. That is, when you animate, and someone else reacts to it by animating along with you. You stab someone in the heart, they react as if stabbed through the heart. You hug someone, they hug back. Too many games simply have one-sided animations where one character animates and another character animates, but they don't make contact. Oblivion did this, and Morrowind really had no animations aside from attack and move. Havok Behavior seems like very capable technology, so I'm looking forward to its implementation.