Not an expert, but how many people you pack in the space, what noise level you expect them to generate, and how loud you intend to play music would be a big factor. Not to mention any objects in the room that would dampen the sound.
For example, if the several booths, many tables closing packed together, where the music will be fairly loud, you would need more speakers than…booths against the walls only, fewer tables, and a more quite fine dining setup with background music only.
Don’t consider using Sonos speakers wirelessly in a crowded setting, unless you can mount them sufficiently high up that the human bodies -- which are mostly water -- don’t attenuate the signal.