I'm looking at a similar issue since I've just punched my ticket to the playoffs and I've been streaming D's all year.
I'm leaning towards Bills (home v Seattle) week 15 and Colts (@ Chiefs) week 16. Its possible we'll see another QB go down like Cutler/Vick/Roethlisberger in which case everything could change.
Homer: [looking at watch] Two hours? Why'd they build this ghost town so far away?
Lisa: Because they discovered gold over there!
Homer: It's because they're stupid, that's why. That's why everybody does everything.