setup of 6x Era 100 SLs

I don’t think the hotel wifi is going to work. Most hotels have isolation between connections so guests can’t interfere with each other. One thing you can try is using a travel router/wifi access point that you control and have your phone and sonos devices connect to that.

Since the Sonos are to use for the hotel at the public areas , don't think the travel router or the WiFi point will be a solution because the distances between the 6 of them won't be closer enough to work all with one router. I think 

The best way to have this working the way you wish is to hardwire each speaker to your network, which will require proper STP/RSTP and multicast settings. Having them on a specific VLAN (like your IoT VLAN), with a single device connected to that VLAN to control the Sonos speakers, would be your best bet to avoid connection issues and dropouts. I would not use them wirelessly for this deployment.

Ask your IT department for help with this. I am sure there are a few VLANS already created for different departments as well as things like servers.

Also, you can ask your IT folks to ‘whitelist’ your Sonos devices, so they can talk to each other, and have reserved IP addresses. 
 

Talking to each other is one of the most important things for Sonos speakers. As previously stated, most hotel networks don’t allow this, for ‘security’ reasons. 

I recommend exploring the Sonos Zone setup in the link as well as the Era 100 Pro and Zone Guides in the sub-links.

https://support.sonos.com/en-us/article/set-up-a-zone-for-multiple-sonos-products