Now that I've shelved my TYP cards, in a typical month I'll use the following cards, in order of priority (for this year):

1) BA Visa -> Until I reach $30k, then it will get shelved
2) AMEX Platinum -> Groceries and gas (at least while they still offer 2x miles) and then AMEX MR mall in cases where the 4x is better than other 'rebate' sites (e.g., Staples.com).
3) HHonors AMEX -> Hilton hotels, cell phone and cable bill. Will revert to my primary card in 2011 until I hit $40k (which will take me most of the year).
4) Diners Club -> Rental cars, will be my primary card this year once I hit $30k on BA Visa.
5) US Airways MC -> US purchases (have it for the 5k mile discount on US award tickets)
6) Discover -> 5% rebates and some decent online shopping mall partners (e.g., VisionDirect for my disposable contacts)
7) SPG AMEX -> Costco when I'm not focusing on my HHonors AMEX (last year I was, next year I will) and the rare stays at SPG hotels