The Official Marriott reply:
Thank you for contacting Marriott Bonvoy in regards to the Platinum Elite benefits and upgrading you.
I hope that you are enjoying your stays with us and the upgrades that are available to you when checking into the hotel.
The benefit of a complimentary upgrade to the best available room subject to availability does not include Suites. When you have 50 Nights a year, you will be offered an Option to select 5 Suite Night Award request forms to upgrade to a Suite if one is available to you.
Some hotels will upgrade you to a Suite if one is available, however that is a courtesy offered by the hotel at the time of checking into the hotel.
We appreciate your loyalty to Marriott Bonvoy and look forward to hosting your next stay with us. If you need assistance booking your next stay, please do not hesitate to give us a call at 1-888-625-4988.
My Point in this:
Marriott Reply: "The benefit of a complimentary upgrade to the best available room subject to availability does not include Suites."
Marriott Terms: "Complimentary Enhanced Room Upgrade for Platinum Elite Members. Platinum Elite Members and above receive a complimentary upgrade to the best available room subject to availability for the entire length of stay at the time of check-in. Complimentary upgrade includes suites,"