I don't think I could live without frostfall and realistic needs and diseases. Just adds some immersion without being overly tedious.
Vilja in skyrim, if you are a packrat that hates leaving loot behind that lady can carry quite a bit. She can also make runs to the shop for you if in town, make basic potions on the run, set up a camp, cook. Also makes for a nice sparring partner if you want a bit of a safer environment to level up your combat skills some in a safer environment.