I agree with the comments on previous answers that the main site and meta have two different purposes. It may be useful to send out Tweets for both, but the tweets should not be mingled in the same Twitter stream.
Tweets from the main sites are public-facing: they are intended to draw users to the site to answer the question if they have an answer, or to read the answers if they need an answer to a similar question. My question is, who is the intended audience for these tweets? Are they only for people already participating on Stack Exchange, or are they intended to draw new users to the site?
Tweets from Meta are public town-hall meetings, but even within that sphere, there are different types of meetings. Cities can have regular bread-and-butter sessions, which are of little interest to anyone not a policy wonk, unless there happens to be an issue on the agenda which directly impacts you. Contrast these with Public Hearings, special issues where input from the Public is solicited on that general topic.
I think it would be useful to separate these Twitter streams, so that those who chose to follow the sites on Twitter could choose which kind of Tweets they wanted to get.
Ideally the only kinds of Meta posts I would like to see included in the main site's Twitter are the public-facing ones, like announcements of events (Weekly Chats and other events, Weekly Topic Challenges, and the like). These could be selected by means of a tag like featured.
I understand the argument of Tweeting the everyday Meta content for those who are already on the site, but I would like to see Meta sites on a separate account, so that the people who want to keep up with the site via Twitter chould choose to read it.
We don't mingle Meta posts with the posts on the main sites -- we have separate areas. There are all sorts of good reasons why not -- and IMO those reasons apply to the Twitter feeds as well.