New Bar Installation

I would go with two play:5s myself. The Sonos Ones are great, but a little lacking for that space, and don't have the same bass as play:5s. You could also go with One and a Sub, but you're spending more than 2 5's in that case.

Two 5s would give you the power you need to have the music audible over a crowd.
One thing that is not Sonos related: isn't it a violation of Spotify's terms and conditions to use it in a commercial space?

And I don't think you'd be playing Spotify off of a tablet, either. Technically, you'd be using your tablet to tell the Sonos to go out and get the Spotify stream.

Fenners83

I find it difficult to recommend which Sonos for X space just based upon 580sq ft. Is the space a square or rectangle or maybe L-shaped? Where is the bar area located vs general seating. As the music is mostly background I would think deep bass not to be a priority. Several Play 1's might be the better solution. I wouldn't choose Sonos One's as you don't want the microphones active in a bar setting and the Play 1's deliver the same sound. Still in the end Play 5's may be the right choice. :? Submitting a diagram IMO would allow for a more informed recommendation.

Cheers!

Also, consider running the speakers wired, not wireless. Human bodies absorb WiFi signals beautifully, plus most of those bodies will be carrying their own source of WiFi interference.

And I would reiterate Sjoop1985's warning about terms of service.

In most cases, commercial use of the product (music) requires different licensing than is covered in the normal license for home use. Sonos doesn't care how you use their product, as near as I can tell, but you may be liable for penalties from Spotify. Note I said "may be". I'm relatively certain that there are many cases of this kind of thing, and I've never heard of any streamer going after someone. However, having run a few restaurants in my time, the lawyers I dealt with were pretty careful about making sure the Muzak service I used (this is back in the 80s) was appropriately licensed.

To echo the warnings of Airgetlam and Sjoop1985 you may have to contend with ASCAP and BMI licensing if in the US; even though you may own the music on your device for private listening.

https://entertainment.howstuffworks.com/music-licensing3.htm

Fenners83
I find it difficult to recommend which Sonos for X space just based upon 580sq ft. Is the space a square or rectangle or maybe L-shaped? Where is the bar area located vs general seating. As the music is mostly background I would think deep bass not to be a priority. Several Play 1's might be the better solution. I wouldn't choose Sonos One's as you don't want the microphones active in a bar setting and the Play 1's deliver the same sound. Still in the end Play 5's may be the right choice. :? Submitting a diagram IMO would allow for a more informed recommendation.

Another thing that comes to mind after reading this:
When you eventually do scatter speakers around the space, I would recommend setting them up as separate rooms and grouping them, and not to set up stereo pairs, even if you only go with two speakers. Stereo separation won't mean much in such an environment, and with actual stereo recordings it would likely sound strange to people closest to one of the two speakers in the pair.

To echo the warnings of Airgetlam and Sjoop1985 you may have to contend with ASCAP and BMI licensing if in the US; even though you may own the music on your device for private listening.

Indeed, this is the case in Europe as well, so not only Spotify, but any music you play in public or in a commercial space will be subject to some form of licensing.

Another thing that comes to mind after reading this:
When you eventually do scatter speakers around the space, I would recommend setting them up as separate rooms and grouping them, and not to set up stereo pairs, even if you only go with two speakers. Stereo separation won't mean much in such an environment, and with actual stereo recordings it would likely sound strange to people closest to one of the two speakers in the

Also, by not setting stereo pairs you can control the level of each speaker individually. You may want the audio higher in one area and lower in the other.

Cheers!