If you want your guestS to use bluetooth, what’s the use of Sonos (a WiFi enabled system) for you? Would it not be easier (and probably cheaper) to install Bluetooth only speakers? This way you don’t have to worry about WiFi a feauture your clients would not use anyway.

There are a few things I see that could go wrong with implementing Sonos for hotel room audio.

1. Even though you only need internet to do the initial setup of the Era 100, disconnecting them from the network would be a MUST.
2. If left connected to a network, you still have to figure how/if to grant access through WIFI, because many people use Spotify or Airplay. Each room would need to have its own VLAN and WIFI, so that other rooms would not be able to see other speakers in other rooms.
3. The web app could also pose an issue. If someone somehow get login information, they could wreak havoc on guests in the middle of the night.

As ​@106rallye stated, a simple Bluetooth speaker may be the better and less expensive route.

I don’t think SONOS would be a good choice for this application. SONOS is designed as a home system, not a hotel system. There will be constant issues that your staff will need to be able to deal with -- starting with the “smart” guests who will Factory Reset the SONOS units in order to use their own SONOS controller and play their own music using their own travel router. There will be requests from guests who are using multiple rooms wanting to play the same music through all of their rooms. While this can be accommodated, you’d need a very sharp staff person available to setup the rooms, give user instructions, then reconfigure the units back to the regular settings after the guest signs out.

There’s also a limit to the number of devices in a system so you’ll need multiple accounts, adding to your administrative requirements.