I personally like Calvin tomorrow for the simple fact he's supposedly fully healthy and it's possible they fall behind and go to the air a ton. He is risky though because the bengalslike to run a bracket coverage on the other team's number 1 that has really shut some people down. However, I personally tend to look for a large volume of potential targets and that's what Calvin should see if they get down a few td's quickly.
Chambers is tricky because he will likely see a real good amount of champ bailey; however, he is clearly thriving in the number 1 role in KC. I'd be cautious though as I don't see him being good enough to dominate a good pass defense with a bullseye on his secondary. I can see that game being fairly low scoring.
Kenny britt has been very good in the last few weeks with justin gage out, but I am not sure if he will be back?? I'd actually consider starting Britt if Gage is still hurt. Vince young has actually been passing pretty well as of late, and Britt is also a nice big goalline target. Colts secondary also has some injuries, and against the Colts there is again some possibility of falling behind and being forced to air it out.
I would actually be inclined to bench garcon first personally. He is obviously in a great offense, but he is the most likely of all your receivers to get lost in the shuffle with Wayne, Clark, Addai, etc. and not get the looks to put up a serviceable stat line. It's not that Garcon is incapable of having a big game, but rather he is just less likely than your other receivers that are primary targets.
Crabtree could be useful- he is putting up at minimum decent yardage totals every week and seattle's pass defense has been very vulnerable. He has had an unfortunate lack of touchdowns though (I believe only 1? Vernon Davis is taking them all).
Hopefully warner plays because Fitzgerald brings a level of consistency that is unmatched as far as receivers go- I believe he had over 20 straight games with at least 7 fantasy points before last week, so Leinart is bad news.
My take- Fitzgerald, Calvin, and Britt if Gage is out, otherwise Crabtree. Receivers are tough to pick, but your best bet is to go with the guys who will get the looks