Well, one should definitely be obvious: Charles. He's going to see the ball 25+ times since KC's backfield is, well...for all intents and purposes, Charles is
KC's backfield. He's been great recently both on the ground and catching the ball, and Denver's defense is suprisingly marginal against the run.
Grant and Maclin is a tossup. With Grant going against a solid run D, you know what you're getting: 70-80 yards, maybe a TD. Let's say he's getting an average of 11 points. Maclin is intriguing because Jackson likely (definitely? I haven't checked the injury reports) won't be in the lineup. The way Philly airs it out, I'd be shocked if he didn't find paydirt. IMO, he'll put up something like 6/90/1TD. I almost always go with the RB in a situation like this, but considering what I think is Grant's limited upside and Maclin's limited downside, I'm leaning toward JMac here.
Here's mine: http://www.fantasyfootballcafe.com/forums/viewtopic.php?t=463571