Beat me to it!
Playing as House Dayne right now, and Dorne's a mess. All of the highlords, myself included, keep revolting and starting factions against the Princess of Dorne, but her son, the Storm King, keeps coming to her rescue. She just revoked Starfall from me...
I also have a Bolton playthrough going on, where all the Starks died off, I made the North elective, ruled it for a few generations, lost it, and now am the Lord Paramount of the Riverlands.
My best vanilla game has to be my House von Nordheim campaign, where I went from Dukes of Bavaria to King of Jerusalem, Poland, Hungary, Bohemia, Italy, Germany, and France in that order. And my dynasty is also on the thrones of Denmark and Mauritania (and Portugal). I think I'm in the year 1442 now. Also in that game, the Teutonic Order conquered pagan Sweden, and I then vassalized them so that was pretty cool.
The Jimenas are Kings of Castille, Aragon, Leon, and England. There's a Russian Orthodox Rurikovich on the throne of Norway and Scotland. Pretty interesting game overall.
Thinking of starting as the Count of Carcassonne next...