Agree with above on Addai. Don't even think about benching him. He'll be good for 100 or so total yards and a score--pretty much a guaranteed 15+ points.
For the second spot, I think we can eliminate Edwards, Bennett, and Floyd right away. Neither has been anywhere close to consistent enough to consider starting over the other three. The next guy I'd cross off the list would be Chambers. He's been a model of volatility during his tenure in the league, so there's no way I can trust him. He had a pretty pedestrian game last week aside from his huge catch in overtime, so I don't think there's too much to get excited about there. I'll need to see him play well for another couple of weeks to consider playing him over a guy like Walter. That said, I think I'd go Charles over Walter. In a battle of a #2 receiver vs. a starting RB, I'll always choose the RB because of the guaranteed touch factor. Walter could very well have a big game, but the guy most likely to get 100ish yards and a TD? Definitely Charles.
So, Addai and Charles.
Here's mine: http://www.fantasyfootballcafe.com/forums/viewtopic.php?f=19&t=462822