Yesterday saw us combining errands (and splurging on a movie... Wanted).
We ended up getting four free loaves of bread at the bakery outlet place, because we finally filled up the card. Unfortunately they no longer do the punches : (

So thought for the day: Even though the store cards track your spending, you can still save money, so I say, "Sign me up."
And if your wallet/purse is getting too fat, keep them in your glove box and just pull out the card you'll need for whatever store you're going into.