I like to imagine things that would totally knock my socks off...
1. Night and day cycle, moon phases, solar eclipses, auroras, varying clouds, shooting stars, seeing different planets from afar, severe weather and environments, a whole new ambiance.
2. Different array of creatures: canines, felines, equines, cervines, rodents, reptilian.
3. Totally different customizations: sizable, colorable, different styles of ears, tails, wings, eyes, paws, claws.
4. Quests that go in depth, add insight to your characters, the proof of knowledge within the world.
5. Magicka; spells, alchemy, potions.
6. In depth lore placed everywhere, even within the characters themselves. Each character have special attributes due to where they hail from.
I mean, that's just my personal preferences. >_<;; I can only achieve these whimsical things are from writing and reading books.