There isn't an easy way to use them. Every so often amex has a promo- buy a few cards and we'll send you a $25 bonus card. I've participated in the last two promotions, but I always end up with a few hundred bucks in amex cards to burn off. End up using them to buy store gift cards and spend them on purchases I was going to make anyway- which is fine in most cases, but realize then you're losing the original opportunity cost of just using your credit card on those purchases (especially if you have select spend bonuses- like on gas, groceries, drugstores, etc.) And you lose all the great perks of a platinum card, like extended warranty, purchase protection..

It was worth it for me (2x $25 gift cards, minus 2x $3.95 activation fees, plus $25 bonus card still puts me ahead $17), but if you're just doing it for miles it probably isn't. If you want to give the cards to your nieces and nephews for christmas, then go for it by all means