Just helped a customer today with Spotify and Sonos. Although you can control Spotify through Sonos, he mentioned there were several features in the Spotify app that you cannot access through the Sonos app. I think one of them was some kind music channel.

I had to create a Sonos login account for him, and then you can link up the Sonos system to the Spotify acccount - from there you can play music from the Spotify app directly into the Sonos system with control.

Seems like Spotify is being a little beeatch and making life difficult.