What are your best solutions for UI commentary? I work for a hospitality company. I'm looking for the ability for each of my GMs to comment in the UI when their property is selected and others see these comments when selecting the property.

No, Tableau will never write-back natively. It's a visualisation tool, so it shouldn't write back at all.

There are extensions that you can use to do this, or develop your own to complement the dashboard, but write-back should never be added as native functionality.