I think Sitefinity would be a very good solution to your particular scenario and here is why. Namely, Sitefinity uses provider model on all of it components (modules, pages...). So if you are to create 3 sites (let's name them A, B and C) and you want all these sites to be individual, but the news you want to share between them - meaning that whenever an individual site publishes a news, it appears on all three sites.
So basically, you would have 3 sites and 3 databases. What you can do is add a new connection string to sites B and C and point it to the database of site A. Then in sites B and C for news module you would change the connection name of the provider to point to the database of site A (using the additional connection string you've added). And this would result in sites A, B and C all being individual, yet sharing the data of news module.
There are of course many different options you can do here. You could add 4th database, which would act like a global database and have all sites use 2 news providers (their own and a global one). Namely, Sitefinity supports multiple providers.
I was talking about news module simply as an example, but surely you can do it with other modules as well.
I hope I was able to answer your question. Let me know if you have any more.
the Telerik team