1. A system, comprising: a plurality of resource collections, implemented by one or more computing devices, of a provider that provides one or more network-based services to a plurality of clients, wherein at least some of the plurality of resource collections of the provider are accessible to one or more of the plurality of clients via one or more private network links and additionally accessible via one or more shared network paths; a plurality of metering agents, implemented by one or more computing devices, one or more of the plurality of metering agents configured to: measure, as a first network traffic measurement, network traffic transmitted on behalf of a particular client of the plurality of clients to obtain one or more services from one or more resource collections of the plurality of resource collections of the provider, wherein the first network traffic measurement includes both network traffic transmitted over the one or more private network links as well as other network traffic not transmitted over the one or more private network links for the same particular client; measure, as a second network traffic measurement, the network traffic transmitted on behalf of the same particular client over the one or more private network links, wherein the second network traffic measurement does not include the other network traffic not transmitted over the one or more private network links, wherein each private network link of the one or more private network links is set up to establish a private network path between a respective client network of the same particular client and a respective resource collection of the plurality of resource collections of the provider; and a manager component, implemented by one or more computing devices, configured to: obtain the first network traffic measurement and the second network traffic measurement; determine a differential network traffic amount dependent upon a difference between the first network traffic measurement and the second network traffic measurement; and provide composite information to the particular client, wherein the composite information is based at least in part on the differential network traffic amount.