The Marriott Card has one additional bonus if you ever stay in one of their hotels: as long as you carry the card, you are considered an elite member of the Marriott Rewards program.
Silver status you a special reservations line, priority for room requests (king beds, non-smoking, higher floors, etc.), and a 20% bonus of MR points. Although not a listed bennie, they occasionally throw in a room upgrade at check-in.
Meaningless if you never use hotels, but sort of nice if you have even a couple stays a year.