I use Twitter a lot, mainly for reading. I essentially abandoned RSS for Twitter some time ago (> 1 yr but I forget how long), so essentially all news I read is via Twitter.
Because tweets act like they're ephemeral and seem to act even more so over time (they aren't really but it can be hard to dig up your old tweets), I've backed off to blogging for any message I really care about, and even some that I don't. All of my blog posts go to Twitter via Feedburner.
In the past, I thought Twitter was extremely powerful since it provided an instant communication infrastructure for almost anything you wanted to do on the Internet. The buzz over that seems to have died down. I don't know if it's really old news but I'm sure there are so many examples on either side of that question, it's probably not worth debating.
So, I use blogs and Twitter for almost anything I want to say to groups of people or in public. If you read those two sources, you can see almost anything I've said. For other places like Facebook, Google Plus, I forward the blog and Twitter posts on to them.
On rare occasions, I do post or reply in other places.