1. A system, comprising: one or more computing devices configured to: allocate a set of provider network resources to an application deployed on behalf of a particular customer, wherein a virtual computing service of the provider network supports a plurality of compute instance categories that differ from each other in one or more performance capabilities, and wherein the set of provider network resources comprises a particular compute instance of a first compute instance category of the plurality of compute instance categories; receive, from the particular customer via a programmatic interface, an indication of one or more end-user workflows associated with the application; collect respective sets of performance metrics associated with each end-user workflow of the one or more end-user workflows; initiate, based at least in part on a determination that a particular performance metric of a particular end-user workflow of the one or more end-user workflows meets a threshold criterion, a resource re-evaluation analysis associated with the application; determine, during the resource re-evaluation analysis, that the set of provider network resources is to be modified; and implement one or more configuration changes to modify the set of provider network resources, wherein the one or more configuration changes include a replacement of the particular compute instance by a different compute instance of a second compute instance category of the plurality of compute instance categories.