About great mods with quests and changing the main story, is too soon. Creation Kit is still a baby... But...
ESSENTIAL mods for a
great PC experience:
Unofficial Skyrim Patch
SkyUI (you have to install SKSE -Skyrim Script Extender- first)
Categorized Favorites Menu (also use SKSE)
Quality World Map with Roads
Unique Region Names
Enhanced Night Skyrim
Enhanced Blood Textures
Glowing Ore Veins
Improved NPC Clothing
Sounds of Skyrim - Dungeons
Sounds of Skyrim - The Wilds
sixy Cities (HD textures for cities). Riften and Solitude are my favorites. Amazing work.
You already have DD and WZ. Good. You also can try: OCS -Occupy Skyrim-
Sorry, no direct links, too lazy right now (but all the names are correct, search in Nexus)
I also suggest... Save often, save well. Learn how to do a "clean save" if you want to remove a mod. Use BOSS and Nexus Mod Manager (or similar)... But you already know all that.
