Distinct seasons with more environmental (flora, fauna) dependencies (abundance, existence) on seasons and weather
holidays for NPCs to celebrate and talk about (like in Daggerfall)
the chance that captured souls can escape from broken armor/weapons, or from a failed enchantment attempt (like in Daggerfall)
seeing snow accumulate and melt, seeing rain cause puddles, flowers bloom and wilt
rain to NOT fall through exterior roofs
being able to detect weather and daylight indoors, and to be able to see through windows to the outside
more 1st person non-combat motions: hand reaching out to open door, furniture, pick up item, drink potion, etc
more reactions by NPCs and PC models to weather conditions
see my feet
more town and city life that is more random, with more stuff to do
more NPC dialog specific to location, class, faction, race, local and global politics