An interesting post - due to some past rather ugly occurrences I am particularly sensitive to hotel security issues. One of the main reasons I am a loyal Marriott fan, and have been for years, is that they were the first chain to pay particular attention to the safety of their women travelers. (OK, I am dating myself here, but there was a day when there were not that many of us )

What I think is interesting is that I have never had my key re-keyed when I have asked for a late check-out. Not once. I will have to try it and see what happens - perhaps I have not asked for one recently.

A bigger concern of mine with regards to security (hope you don't mind if I build off your post) is setting up the smoking area right outside the side or back entry doors. (CY, SHS, RI in particular) There are times when those doors are the most convenient to use; but if there is a lone smoker there, I will not do so. If they ask for access as I enter, I would not feel comfortable giving it to them - but I also am not going to ask to see their key! It seems this is an "easy" way to access the building and certainly bypasses the security system of a keyed entry.

I know Marriott doesn't want them standing out front, so am not sure where the correct location should be ....