A service provider can efficiently allocate server computer resources to tenant users, while isolating tenants from such allocation decisions. A tenant specifies a desktop model to be used for virtual desktops to be provisioned for a pool of users. The service provider has desktop managers for each tenant, each of which manages a homogeneous set of server computers to be used for provisioning virtual desktops for the tenant. Different desktop managers for a tenant are used to manage different sets of server computers to support virtual desktops using different desktop models or desktop models with different resource requirements. A resource manager of the service provider assigns virtual desktops to a desktop manager in a manner that optimizes the utilization of the server computers by using information about the desktop model used by the virtual desktops.