Neither you, or the guests, have a legal expectation of privacy in public places, such as the hotel lobby. Furthermore, you have no legal expectation of privacy at work and can be video recorded, audio recorded, and photographed anywhere at work other than the bathroom and the designated area for changing clothes without your consent and without notification. The "one party consent"/"two party consent" (as in some states you need consent of all parties to an audio recording, and in others as long as the person doing the recording is a party to the conversation it's ok) analysis only applies to conversations in which there is a legal expectation of privacy. As explained above, there is no legal expectation of privacy in public places, and in a string of decisions spanning 1967 to 2010, the US Supreme Court has made it clear there is no such think as "workplace privacy" in the United States.
We do not have an attorney-client relationship. I am not your lawyer. The statements I have made do not constitute legal advice. Any statements I have made are based upon the very limited facts you have presented, and under the premise that you will consult with a local attorney. This is not an attempt to solicit business. This disclaimer is in addition to any disclaimers that this website has made. I am only licensed in California.