I've really come to appreciate the container feature, but they're still completely manual.
I'd suggest to add a feature to bookmarks and bookmark handling, so that I can specify in a bookmark, in which container it will open.
The idea is to have e.g. one bookmark "Google/Docs/YT (work) to open in my "work" container with my work login, and another one to open in a standard container with a different or no login. Currently, this works just fine, but I have to open the container tab manually each time.
(This could be a more flexible addition to pre-assigning e.g. all *facebook.com domains to one container as @bugboy suggested.)