I used a gift card at the Grand Bohemian in Charleston last week. I heard that hotels seem to have issues with applying them to your bill. In anticipation of that, I went to the front desk early in the day of check out. The clerk asked if I could leave the card with him so that he could figure it out. When I went back to the front desk later all was good.
I couldn't book online because they needed a credit card to book. When I called to book, they charged me a deposit. The front desk was able to apply my gift card to the balance of my bill when we checked out.
Dear Marriott, there's got to be a better way to book a room and enter gift card online.
dh