My girlfriend works at the Golden Nugget as a manger and has informed me that they do not permit Open Carry, But, one you are checked into your room, you are protected and have certain rights. They can prohibit open carry on their property, but they cannot keep you from coming and going. If you are on your way out or back in to your room, you can open carry to and from, but if you are using the services and amenities of their hotel, they can ask you to secure your arms in your room or with the security office.
Your hotel room is part of your home, and is protected by the Second Amendment. The rest of the hotel and casino is fair game for them to set and enforce whatever policy they wish provided that it does not exclude a protected class. The RKBA is not a protected class there.