I currently have dots all over the house, and Sonos. The missus very much likes being able to ask Alexa for all manner of music, but wishes it would play with the quality/ubiquity of the Sonos (agree with previous audio quality comments, it’s not HT level, but it’s pretty solid for the size it is). Amazon has hinted a few times at adding multi-room functionality (presumably to compete with Google Home), but nothing official has been said one way or the other. I have Sonos set to trigger pandora stations/Google music files for various events in ST using Notify with Sonos, and it works fairly well, but not to the degree of flexibility you’re asking for.
Just a heads up what’s coming down the pike… come on 2017
There are also custom script options to get Sonos integrated into Alexa/ST today, but they’re not for the technologically faint of heart.