As everyone knows, it is not easy to find Marriott cat 5 properties in where you intend to visit. The question is if the Marriott annual certificate can be redeemed in a SPG property?
Nope! See all the posts, comments, etc, including the Marriott FAQ about both rewards programs operating as separate programs until the combined rewards program is formed in late 2018, early 2019 or so.
But, you can find the 700+ Cat 5 Marriotts here: https://www.marriott.com/hotel-search/Category5.hotels/
or, all Cat1-5 Marriotts: Book Category1 Category2 Category3 Hotels
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