For those doing multiple cards at the same time I've got to add this little tidbit.
Do one transaction (use coupon, redeem miles etc), confirm transaction posted properly. Take it to the car, pick up your list for next transaction, repeat. etc. Last year when doing multiple in a row I found it is so easy to get mixed up with all the coupons and cards. You want to have a process for checking out (goods, AM card, coupon, cash/CC or whatever works for you). Keep saying it over and over in your head. This is not the time to have a nice chit chat with the cashier about the weather. Serious stuff! Errors can easily be made by the collector and the cashier. Keep those eagle eyes on the prize.
Just my experience (but it cost me a few cash miles when I didn't pay enough attention). It's worth the extra steps to the car to clear your head and regroup.