I'd like to get some opinions from the more experienced travelers here at FlyerTalk. I'm not trying to start another useless "This card is better than that card" thread. What I *am* trying to do is figure out the best way for me to maximize the number of miles/points I earn from purchasing things I was going to buy anyway, and to see how the "pros" (that'd be you guys) handle your cards.

It's pretty widely said that the best overall card for earning miles is the Starwood Preferred Guest American Express Card (which I own.) While there are obviously a zillion other cards, with great signup bonuses to plump up your mileage accounts, most folks and FF websites consider the SPG AmEx to be their number one "everyday" card.

But I'm wondering, if you can buy something through the Shopping Portals, like AAdvantage eShopping, United's Mileage Plus Shopping, or the AmEx Bonus Points Mall, then won't that give you the most for your money?

Example: Let's say that you're going to buy a new laptop, say, an Apple MacBook. For the sake of argument, we'll say it costs $2000. If you buy it with your SPG AmEx, you'll get 2000 SPG points, which ultimately could be worth 2500 points with their 25% bonus transfer. But if you were to buy that same MacBook through Bonus Points Shopping with a Platinum AmEx, you'd earn triple miles - 6000 MP. If you bought it at Continental's ShopOnePass with a OnePass Mastercard, you'd earn quadruple - 8000 miles on Continental/Star Alliance.

To make this decision even more complex, of course, not all points are considered equal. I understand that SPG points are highly valued because of their flexibility. For example, 2500 SPG points might be considered more valuable than 6000 AmEx membership points. Or they might not.

For the purposes of this thought experiment, forget about bonuses. How do you make your decision about which card to use to make everyday purchases?