Add Boston and Miami to that list.

Can absolutely confirm that offer extends to primary supp cardholder too (or anyone else that has a black coloured card on your account - so if you pay the extra £650 in the UK). We have used it multiple times in the last 5 years doing 4 night stays (2 nts in my name, 2 nts in my wifes name).

On a separate note, the buy 1 night, get 1 free at the city Jumeriah properties has been extended and can be used as often as needed by any cardholders on a Centurion account. My parents are currently enjoying their 4th free night at one of the London properties this year.