If you aren't already aware, there's a dedicated Skyrim mods community over at skyrimmods@lemmy.world. (EDIT: Though I realize this community isn't accessible to those on Beehaw because of the defederation 🙃)

But to answer your question - I've been using Populated Skyrim: Hell Edition in my latest playthrough, and it's awesome how much more alive the world feels. Plus, having more bandits and adventurers on the road makes for some pretty awesome spontaneous encounters.

I also love skyrimlazz's castle mods for late-game dwellings.