My plan: 3 sites with identical content, yet--wait for it--for every article whose topic is A, the pages on all three sites posting that article will have a rel=canonical tag pointing to Site A. For every article whose topic is B, the pages on all three sites posting that article will have a rel=canonical tag pointing to Site B.
So Site A will have some articles about topics A, B, and C. And for pages with articles about A, the rel=canonical will point to the page it's on. Yet for pages with articles about B, the rel=canonical will point to the version of that article on site B. Etc.
I have my reasons for planning this, but you can see more or less that I want each site to rank for its niche, yet I want the users at each site to have access to the full spectrum of articles in the shared articles database without having to leave a given site.
These would be distinct brands with distinct Whois, directory listings, etc. etc.
The content is quality and unique to our company.