Vaguely, I want to see more of Mab's long-term plans and goals. She's been moving pieces around for ten or eleven books now, and I want to start learning why (from her perspective, not the Mothers or Harry's often warped interpretation).
I'd like to see how Marcone handles himself among the major players. This would be the first time on-page of him negotiating and dealing with Big Supernatural Things. Not really an ongoing plot clue, but it's something I've wanted to see for a while now; Marcone staring down Lara Raith in particular would be fun.
And, like others have said, we need to get the White Council back into things; they've been missing entirely for three books, but really four (as their only real contribution in Changes was to introduce a new jerk and then get sidelined).