I have enjoyed coming to AP readings for years, in part to learn how to better teach my students to do well on AP exams, but more so for the friends that I have developed over the years. One of the people I hang out with is Dan Larson (AP Government) who along with his colleague Andy Conneen (AP Comparative) have create a tremendous website called CitizenU. Their premise and I whole heatedly agree is that our current textbook models is dying. So for the past two years they have create their own website and not handed out any books (and are working on a similar one for AP Comparative).
The CitizenU size is divided as you would see any book with foundations, Congress, Executive, etc. Then within each unit it has resources, assignments, the basics, video and more.