Stories need characters you can relate to. The plot has to be surprising, leading to thoughts about the world that are interesting and universal. (source)
That, in a nutshell, is why I find it so difficult to make science not just accessible, but interesting to non-scientists. As scientists, our characters are data and ideas, not people. Our plot is the unraveling of a mystery, but it's a mystery about nature not about people.
But I'll keep Ira's advice in mind every time I write about a new finding here. I'll try to find a character -- a person -- who's affected by the story, even if it's the scientist responsible for the discovery, and I'll try to formulate a story with a surprising and universal plot. Please remind me when I fail.