The hardest place to get a late checkout IME has been the Orlando World Center Marriott. The normal checkout time is 11 am, and I had to pull teeth to get a noon checkout. The other instances which required more effort were at a CY near Orlando. However, I would go back to that CY because it has a good room rate and is close to stores and restaurants.

On the other side, I have gotten late checkouts approved in advance at the Washington Dulles Marriott Suites when a certain manager was working at the front desk the night before checkout. I discovered this the first time when my folio under my door showed a late checkout of 3 pm on the day of checkout (1 pm is the normal checkout).