Money magazine's June issue names the Blue Cash from American Express credit card as the top card for people who are "big spenders." The translation of this is: if you charge a lot, this card can make you a ton of money.
The review talks about the lower level of rewards on the card being modest (which is why I asked for ideas recently on how to get to the top level faster) but then raves about the card once the top level is reached. It says:
On spending above that [above $6,500], things get pretty appealing: You'll receive a fat 5% on the purchases specified above [supermarkets, drugstores, and gas stations], and a still-decent 1.5% on all other transactions. And since AmEx likes people riding high on the hog, there's no cap on the rebate no matter how much you spend.
For more thoughts on the Blue Cash from American Express credit card, see these links: