Give room dimensions. Do you expect to use a microphone for the instructor? What type of speakers do you want to use? In-wall? Wall mount? Desktop? Would you want a capability to go battery operated portable? What will be the source of your music?

Note that in this professional/public use of music you’ll need to setup proper licensing. SONOS PRO might be useful for you.

If you cant run classes without music, installing Sonos in your studio seems like a bad idea IMO. 

How loud do you want the music? That impacts the speaker type and number answer.

As you are looking to integrate Sonos into a commercial environment I suggest you visit the Sonos website and click on the sub-heading links below:

Professional > Pro-grade Sound

• This solution ensures the best Sonos gear is chosen for your business. Systems designed using this Sonos exclusive are connected using Ethernet not only to deliver sound; but also Power over Ethernet (PoE). The advantage being that radio wave interference is greatly reduced; as well as that caused by human bodies which can interference with Wi-Fi. 

Support > See All Services > Licensed for commercial use

• The services listed are certified for commercial use and eliminates copy and/or digital rights violations.