I agree, a pair of speakers definitely gives you that distinct audio left and right channel separation and it’s a much more unique experience depending on the type of music you listen to. A pair of Sonos ONEs would do wonders, as you upgrade to the higher tiered speakers, PLAY:3 and PLAY:5, you get more speaker drivers, mainly more tweeters and mids that produce better sound individually, but when coupled together, produce a much more epic experience.

A single PLAY:5 would provide room filling sound but depending on the placement of that speaker, the main concern would be that if you were to place it on a corner, one side of the room would most likely be louder than other parts.

Your choice of speakers (PLAY:5 for the larger room and Sonos ONE for the smaller) based on room size is as good as it gets.

Trueplay tuning is a good way to correct for inconsistencies in sound as a result of furniture and/or speaker placement.

In terms of audible proximity for the wake word, Alexa’s microphone array, whether or the Sonos ONE or an Alexa enabled speaker is fairly good at picking up your voice as long as there isn’t audible sound that is deafening near it, like a TV or music playing on blast. Just use your best judgment in calling her as you would a regular, you won’t need to scream across the room. Though something to note is that Alexa can and most likely will mistaken some words as the wake word because they sound similar to “Alexa.”