On the trip that I took just last week, at every hotel at check-in, every associate offered me late check-out and even mentioned 4pm as part of the elite schpeal. I declined all offers with thanks, schedule not permitting/requiring it. This was Europe however, an entirely different hospitality world than the U.S., even though still Marriott.
I Recently stayed at a CY and they refused to guarantee the late checkout. after arguing with them, they relented and offered a much needed 1Pm.
2nd time in two weeks I had to argue with a hotel over the "guarantee 4 pm". The first time I had to call Marriott rewards CS and ask for their help.
I just finished a stay at the Envoy Hotel (Autograph Collection) in Boston. I requested a 3 pm late checkout when I did mobile check-in, and reconfirmed when I checked in. I got it with no problem. I also received an early check-in of noon time (via mobile check-in request) for the same room as well. If it keeps working like this, I'm a fan!
The 4 PM is a guranteed checkout as per Marriott website. https://www.marriott.com/marriott-rewards/member-benefits/get-more-rewards/guaranteed-late-checkout-faq.mi
Guaranteed late checkout is an enhanced Elite benefit for Gold & Platinum members, offering late checkout guaranteed as late as 4 PM that can be requested through voice reservations, Marriott app via the mobile check-in process, at the front desk during check-in, or on the day of departure. This benefit is guaranteed at all participating Marriott Rewards hotels, except at resort and convention hotels, where it is based upon availability. Marriott Vacation Club® is excluded.