Techniques are described for managing various types of content and devices, such as via a GUI of a Content Management (“CM”) system executing on a computing device. In some situations, the content being managed includes television-related programming content and/or other types of content (e.g., one or more channels of scheduled digital music and/or on-demand digital music, photos and other images, etc.). In some situations, the managing of the content includes identifying groups of devices via the GUI to present or otherwise interact with various types of content, and to controlling one or more of the devices in various ways. The groups of devices may be of various types, such as content presentation devices of a particular type, content presentation devices that are currently located in a particular location, or content presentation devices or other devices that otherwise share one or more indicated attributes of interest.