As the title suggests, it would be useful to be able to explicitly select which Sonos device is elected as 'root bridge'. This would permit the user more control over which 'tunnels' through the wireless mesh the Sonos nodes choose to communicate with one another, with the aim of addressing dropout or network instability problems.
Whilst use of an STP-capable external switch does allow some control over root bridge selection by making *it* the root, even this may not result in the ideal topology of active 'tunnels'. Indeed what constitutes the best topology can sometimes change, for example when relaying uncompressed Line-In sources between adjacent ZonePlayers which would otherwise be at the extremities of the Spanning Tree.
The Sonos system apparently manipulates bridge priorities internally so as to steer root bridge election, thus over-riding the default selection of lowest MAC address. It's understood that the first node to be registered is appointed root and retains that role unless it's removed from the system. Sonos Support can evidently change the selection of root bridge by accessing the system remotely, so this request is in essence for the exposure of that facility to the user. Factory resetting the system and re-registering everything, starting with the desired new 'root', is a painful alternative.
It could be argued that offering this facility strays too far from the "it just works" philosophy, but those with more complex networks may be using managed STP-capable switches and already dealing with such concepts. The option could be presented to the user under 'advanced settings' with a relatively simple rubric regarding its possible effect. Lacking a visible depiction of the resulting Spanning Tree state would mean an element of trial-and-error for the normal user (assuming no access to the diagnostics), but then so does the selection of wireless channels at present.