Update 9/18/24: They now offer 1,000 bonus Marriott points for someone who is a new member of either Marriott Bonvoy or Starbucks Rewards who joins and links accounts. (ht Dansdeals)
Original Post 6/18/24:
Starbucks & Marriott have announced a partnership. The partnership provides the following:
Earn 100 Marriott Bonvoy® points. When you make three qualifying purchases at Starbucks during any Marriott Bonvoy® Week
Earn double Stars at Starbucks. On days of eligible stays at hotels participating in Marriott Bonvoy.
The Marriott Bonvoy Weeks might be useful if you normally make three purchases at Starbucks during a week anyway. Overall a pretty weak partnership but might as well link accounts (you also get an entry into a sweepstakes when linking an account), although it’s possible they will offer Marriott points/Stars in future for linking so might be worth waiting.