I'm looking to extend both the main SSID and the separate guest network from an airport extreme base station for more range. What apple networking hardware is needed? I presume two express would do the trick, one joining each SSID - but wonder if I can do it with less hardware. Advice or tips appreciated.
Apple express would be your best/cheaper option than getting another extreme. You could use third party hardware, but the results are inconsistent as Apples bridging is slightly different to the standard.
You could use power line networking if you wanted to extended it further than the current wireless network provides. This assumes you're on the same phase of power and wanted to pony up the extra cash.
I jumped in and got two airport express - one to extend the 2.4 GHz network and another to extend the 5 GHz network. The setup is working for more than one day so i'm calling it a success.
It appears a second extreme cannot simply extend all three potential networks (the guest Vlan on the 2.4 channel and the two normal channels.)
I ended up not extending the guest and instead ran an Ethernet cable to move the base station where the guest network was needed and extended the main net back to where the extreme was and Internet access remains.