+1 on this. I have containers set up for Facebook, Google, Microsoft, and Amazon logins (and all the apps they respectively own, that I of course do not have perfect knowledge of).

It's quite clunky to set up though. To add a site to a container, I have to open a new tab in the target container, go to the website, check "always open in this container" in the container menu, then open a new tab, then say "yes, always in this container" at the prompt.