I'd start Vick only because he's playing the Niners. The only good part about that Niners D is that it can stop the run, but the pass is a whole different story. The only person on the Niners D that can keep up with Desean Jackson, Jeremy Maclin and LeSean McCoy is Patrick Willis, but he will most likely be spying Vick most of the game which means that Jackson, Maclin and McCoy will no doubt go ham on that Niners secondary. As long as Vick can be accurate with his throws (which he has proven he can) I'm sure he will have a pretty good fantasy day. At least better than he has in the past few weeks.
I started Fitz....about the only other option since Manning doesn't look like he will be back anytime soon. I think Ima pick up sidney rice and trade B-marshall for Cam Newton