There is a Dining Passport program for the signature restaurants at the Swolphin: Bluezoo, Shula's, Kimonos, Il Mulino. It's a loyalty card that allows you to earn points based on spending; then you can redeem those points for discount certificates to be used at any of those 4 restaurants.
Bluezoo participates in opentable for reservations and the last time I checked, they were one of the options for opentable award redemptions, although it wasn't a very good value (IIRC 2,000 points got you a $10 discount).
If you happen to be staying at the Swan or Dolphin, you may use the Make a Green Choice coupons they issue for opting out of housekeeping for a discount off food/beverage. Prior to the Marriott switchover, each coupon was worth $5 off. I haven't stayed since the switchover, however, and am not certain if that discount remained the same.