Okay, I have many google home devices, alexa/echos, iPhone (homekit), smartthings, ring door bell, ring security, … you name it, I got it.
I can’t find any uses cases to integrate rachio with the home automation system. Other than asking google home to start the water… hmm why?.. does it not run on it’s own? 
What other cool use cases you got?
If i want to run a zone for a little touch up or a test it could be handy to ask for a single zone to run via my voice on my phone. If i just replaced a sprinkler head and need to start/stop it, a voice command would be handy. I’d actually like to be able to specify a run time for a single zone like “run zone 5 for 10 minutes” but it appears you can only start a whole schedule or a Quick Run for a single zone.
The only cool use case for me personally is about to break. I have my Rachio integrated with my Nest Protect devices. I have an integration with the about to be disabled ‘Works with Nest’ program where the Nest smoke alarm will cycle all my zones, wetting down the yard if the detector is in an ‘emergency state.’
Last I read, if you do not move your Nest account over to Google this summer, Works with Nest will still work. But they warn you may not get the best new features that comes with Google Home. I have my doubts Google will offer anything mind-blowing enough for me to break my Homebridge integrations.
I was thinking to turn the sprinklers on when it detects motion in the yard to prevent cat/dogs doing their business burning the turf but it started turning the sprinklers on way too often on people also 
Ring camera needs a “pet” detection mode!
Do you know if you can use Philips Hue Motion Senor instead? I was looking at setting up something very similar; I know you can adjust the motion sensor sensitivity with the Philips Hue. Also, can you set a specific zone that triggers from the motion sensor?
Yes you can use Phillips Motion sensor to trigger a zone, but it needs to be configured through the Eve app.