Search on the Marriott website, not the app. When you search, be sure to check the box for "Use Points". Under the dates selection, choose "Flexible Dates" and a select a month. This will show all dates available on points only for that month. Availability can be sparse, but there is some. Right now there is a whole week in March of 2020 if you are willing book that far out. I had to book a year in advance to get a whole week together on a single reservation, which I believe is required get the 5th night free.