Excerpt from the back of the coupons:

1. Coupon is valid at Marriott, JW Marriott, Renaissance. Not valid ate Courtyard, Fairfield Inn, Marriott Vacation Club, Marriott Executive Apartments, etc. (I would assume that the vocuhers from Courtyard stays are then only valid in Courtyards, Fairfield Inn and similiar, but not in Marriott/Renaissance)
2. Must be a registered guest, and a consecutive 2 night paid stay is required. Only 1 coupon is applicable per 2 night stay.
4. Present Coupon to Front Desk at check-in for credit. Coupon will be cashed-in on bill.
5. Not accepted in gift shop, restaurant, spa, etc.
9. Coupon may be used for all publicly listed and available room rates and packages, excluding catering, group and ontract rates