I love the Amazon Chase card because it's easy. 1% on everything, 3% on Amazon purchases, and 2% on select things like fuel, groceries, etc. Never thought about using for discounted gift cards.
The nice thing is no waiting for a certain amount of points to build up, and I can choose when to use them. They can be applied to the card balance itself OR Amazon purchases.
For me, that's been awesome. No tracking, no hassles. We do 90% of our spending on that card, and then get some "free" money every month from it.