As news reading becomes more social, how do different types of annotations affect people's selection of news articles? This paper reports on results from two experiments looking at social annotations in two different news reading contexts. The first experiment simulates a logged-out experience with annotations from strangers, a computer agent, and a branded company. Results indicate that, perhaps unsurprisingly, annotations by strangers have no persuasive effects. However, surprisingly, unknown branded companies still had a persuasive effect. The second experiment simulates a logged-in experience with annotations from friends, finding that friend annotations are both persuasive and improve user satisfaction over their article selections. In post-experiment interviews, we found that this increased satisfaction is due partly because of the context that annotations add. That is, friend annotations both help people decide what to read, and provide social context that improves engagement. Interviews also suggest subtle expertise effects. We discuss implications for design of social annotation systems and suggestions for future research.