There is a shuttle service that runs between Barbary Coast, The Orleans, Sun Coast, and Gold Coast. On all Shuttles they have a sign that sez "MUST PRESENT ROOM KEY TO RIDE". I have used this service often without a room key. Infact I have never been asked to show it! I think the drivers don't really care much aslong as you give them a tip. Generally a dollar should be enough. Just remember, If you hailed a Cab, It would be a heck of a lot more.
One thing to keep in mind when taking a shuttle: Just be careful because you have to pay attention to what shuttles goes where. In the side window of the shuttle (near the steps to get on) will be a white piece of paper telling you where that drivers travels between. I know there is a dedicated run from Barbary Coast to Orleans only, there is one run that is Barbary Coast to Gold Coast and Orleans, and I know of one that is a Barbary Coast to Sun Coast Only. You catch the Barbary Coast Shuttle off Flamingo Rd. (Side of the Building).
Hope this helps....... Have a great day!!
