Investment expert Paula Pant, writer for Bigger Pockets, offers the one exception for busting out the CC:

If you have $20,000 sitting in a savings account, earning 1% interest, and you want to make a $20,000 purchase on your credit card at 0% interest for a year, go ahead. You have the cash in the bank to pay the credit card in full at a moment's notice. And you'll pocket the 1% spread. Congratulations, now you have an extra $200. (Personally, I'd spare myself the trouble and just pay the card immediately, but if you want to pinch pennies, be my guest.)