User-Influenced Placement of Virtual Machine Instances

A service provider network includes functionality for allowing a customer to influence the placement of virtual machine instances on server computers by specifying a placement strategy. Placement strategies may be shared among customers of the service provider network, and the placement strategies and the publishers of the placement strategies might be rated. Vendor-agnostic placement strategies might also be utilized to identify a service provider network for executing a virtual machine instance. A placement strategy that includes dynamically evaluated parameters might also be utilized to modify virtual machine instances in a customer fleet on an ongoing basis.