I've never tried social engineering before, but a couple weeks ago me and a friend asked for a key card to the hotel room of a colleague and we received it, no questions asked. All we did was ask:
"We need to pickup something from a colleague's room but we don't know his room number and don't have a key. His name is <name>."
They gave us a new key and told us which room he was in.
I know hotel's weren't secure but at least ask for a booking number or something...