First things first I intend to get to know the CK and it's features, maybe write a few pages on the CK wiki that will be up within days of the game being released. Tutorials and whatnot. After that I'm going to use it's fancy and manage-able UI to read all the books in the game (If I feel like it I will probably upload that stuff to the UESP because that's just who I am). I will then look and see what books are missing and start my first mod:
Connected Skyrim
If there aren't roads to other provinces I add those, as well as NPCs that travel to and from other provinces.
Go to any city with a port and add some more sailors and traders, different boats, and make so only some of them would be available at certain times, giving the illusion that they leave and head to other provinces or possibly other port cities in Skyrim.
A library in whatever the capitol is featuring EVERY book from all the ES games. Also going to add some to other houses, stores, caves, etc.
Anything else I can think of until then.
What about you guys?