If you're thinking of using ExpressPay, the contactless payment technology available on new American Express cards such as the Starwood Preferred Guest card, be sure to read this first. I found it in the ExpressPay
Terms and Conditions document.
If your ExpressPay is linked to a Card that allows you to earn points or rewards, you will continue to earn them at the standard rate when you use ExpressPay. If your ExpressPay is linked to an American Express Charge or Delta Card where you currently earn double points for Everyday Spend Purchases you will receive double points on all ExpressPay purchases on the linked account. However, if your ExpressPay is linked to another American Express Card product that offers bonus points or points at an increased rate for spending at particular categories of establishments that accept the Card, you will not receive those bonus points or the increased rate when you use ExpressPay.