With 11 foot ceilings, and a large space, if there is a drop ceiling, I would put in a bunch of 70v speakers throughout the space and a multi-channel 70v amplifier and maybe even zone things up.
You can pick up 70v amplifiers from eBay from Extron for next to nothing that have a fair bit of power and you can add speakers along the way if you would like to. Your source is up to you, but please keep in mind that any commercial space must use PAID audio programming. You can't just put on the radio or Spotify and call it done. You may be sued/fined if you play unlicensed music in a public facility.
I've done a few gyms and basically threw in some JBL or Crestron, or similar 70v speakers with a Extron amp (or similar) and we called it a day.
In a commercial space, putting a few speakers in the corners, then turning them up 'really loud' isn't a good solution. You blast the people nearest the speaker and those farther from the speaker may not be able to hear them as well. Moderate even coverage throughout the space, kind of like the lights, should be the goal.
Something like this, you can get a dozen speakers (or more) quite easily within budget:
Coaxially mounted 165 mm (6.5 in) woofer with butyl rubber surround and 19 mm (.75 in) titanium coated High power, wide frequency response and low distortion for high sound level capability. High power, wide frequency response and low distortion for high sound level capability.
www.ebay.com
Then add Extron XPA 2001 amplifiers to drive the speaker. One amplifier for each ZONE (grouping) of speakers. So if you want 2 groups of speakers, then get 2 amplifiers. They are available for under $50 each and are VERY well respected and sound very good with very high reliability and small size. Ideal for this type of setup.
For example:
Find many great new & used options and get the best deals for Extron Xtra XPA 2001 Power Amplifier XV090015-9001A - SH D3A at the best online prices at eBay! Free shipping for many products!
www.ebay.com
Be aware, the phoenix connectors on the back of the amplifier are important, and while they sell them on eBay, if you find a commercial AV dealer near you and ask, they likely have hundreds of 'spare' phoenix connectors for Extron amps. I literally have dozens at my home that I'm happy to give away. So, check around.