I believe there's an entire thread (recent) devoted to "what's your success rate with late checkout?" (or similar title). Do a search. (In general, it's a good idea to search for existing info before starting a whole new thread on a topic that may have been beaten to death already.)
On the HHonors website, it states, as a benefit to
all HHonors members:
Late check-out upon request: If you need extra time in your room, call the front desk. We'll do everything possible to accommodate your request.
http://hhonors.hilton.com/en/hhonors...mbership.jhtml
This statement ("We'll do everything possible...") is pretty laughable. Many HHonors hotels are downright uncooperative when you ask for late checkout. They might consent to a 1:00 PM checkout (for a hotel where checkout time is noon), but getting anything later than that is pretty rare. This is one of the more annoying aspects of the HHonors program, in my experience.