Just booked my first Marriott Miles+Nights (270K Marriott-->Cat 1-5 + 132K UA).
Then I used the certificate to book 7 nights at the Sortis Autograph Collection Panama City.
I also booked a second room for one night (the first night) with my Chase Marriott CC Cat 1-5 free night.
I then completed the second room booking with 6 nights for 75,000 Marriott (15,000x5nights, plus 1 night free).