The benefit of the charge card (Disclaimer: I have an Amex charge card) is that you can have an extremely large line of credit for those 21-30 days. It's less for balancing your finances and more for spend management (they have great tools to see where all of the money is going, very nice management for multiple family/corp cards, etc).
I'd still trade the charge card for their Costco version.
I'd still trade the charge card for their Costco version.