At MHAFYOS we use $80 chromebits in kiosk mode showing a web page we customize for each screen or group of screens.
For the webpage we use wix so even a novice can customize it with photo slideshows, flyers, message alerts, and calendar events.
We use the free wix package and zoom in the screens to focus on the parts of the page we want, but you could use any webpage and content management system.
It also handles power outages and reboots seamlessly, as this has been a maintenance issue with other signage devices we have used.
The cost is only $80 for each chromebit and no monthly fees.