I know it’s not travel, but it is a good use of Membership Rewards so I thought I’d post: You can get a $25 Gap gift card for only 1,250 Membership Rewards points. You can buy multiple cards at a time, but only $25 cards are half-off.
Theoretically, you could buy $2500 worth of Gap gift cards for 125,000 Membership Rewards points, then turn that into $2,178 via PlasticJungle.com. YMMV on that.
Earn points and get cash back gift cards by using a Gap credit card.