We are running primarily as a micro-services platform and Docker lets us iterate on these smaller units consistently from dev to staging to production. It is also integral to our continuous deployment system for rolling out or rolling back new features.
We use Docker everywhere. Every new service is built in Drone into a Docker image and pushed to our Dockerhub tagged with the git hash. We can then have full confidence we are deploying the exact version of any service.
If there's any platform that's better built for sandboxing, it's Docker. The container infrastructure and Salt have allowed us to build a secure production infrastructure insanely fast from scratch.