1. A method, comprising: receiving, at a storage device, a plurality of data files that each have a file size and that each are associated with a respective device that corresponds to one of a plurality of device types; defining device type pairs that each include a first device and a second device used concurrently by a respective user, the first device and the second device having different ones of the plurality of device types; determining, by one or more computing devices and for each device type pair, an engagement score based at least in part on the file sizes for the data files associated with the first device and the second device, wherein the engagement score represents a degree of usage of the first device concurrent with usage of the second device by the respective user; and generating, by the one or more computing devices, a recommendation message based on the engagement scores for one or more of the device type pairs.