Marriott Rewards is offering a free night promotion for new members that join Marriott Rewards. It is offering a free stay certificate in a category 1-5 hotel after staying twice during the promo period. Your earning period starts the day you enroll through the end of that month plus an additional 120 days. So roughly four months extra plus the month you enroll. If you join now at the beginning of June you have June – Oct 28th to complete the two separate stays.
This is much more generous than the quarterly promotions they offer pretty often that I have taken advantage of. We just used a certificate this weekend for a night away before it expired in June. Certificates must be redeemed within one year of earning them. I earned mine last June and needed to use it by June 12th.
You can register/join here: http://www.marriott.com/marriott/free-night.mi