Experts writing about a topic within their field of research start off with an initial stock of credibility in my eyes, while journalists or other lightweight non-fiction writers have to earn that trust. Heavyweight authors tend to fill their pages with more original and creative ideas, probably because they have actual academic contributions from which to draw on. Lightweights, by contrast, are not direct knowledge-producers and must restrict themselves to analyzing and synthesizing existing research. Often this results in more novel topics and book titles for the lightweights (they've got to find the gaps), but it also means the topics are less ambitious and more marginal.
Malcolm Gladwell might be the best example of a lightweight author: great writing, clever and fascinating topics, tons of cool little analyses and observations. But if I compare his books with those written by actual experts in the research fields from which he draws upon, there's no comparison. Nudge by legal scholar Cass Sunstein and economist Richard Thaler gives a much better overview of behavioral economics and unconscious decisionmaking than does Blink, while Bursts by graph theorist Albert-Laszio Barabasi provides a much deeper and more rigorous understanding of social cascades than does The Tipping Point.
I recently finished The Information by James Gleick (a lightweight), and I was stunned by the complete lack of creativity and original thinking. Marketed and publicized as a deep inquiry into the concept of "information," the book was merely a cobbled-together assortment of different scientific histories (a chapter on linguistics, one on logic, electrical engineering, early computers, etc.). The Hidden Reality by physicist Brian Greene delivered in a single chapter the most fascinating and unorthodox expression of the concept of information I've ever read. So don't be seduced by clever topics or good newspaper coverage (journalists surely promote their own). It's time to get picky and get smart. Read heavyweight non-fiction.