The purpose of virtualization is to separate physical infrastructure from applications. In terms of a CMDB this means you should remove the direct link between ESXi host and VM. In terms of a CMDB it is irrelevant on which ESXi host the VM runs. So your chain goes:
for vCloud Director:
Datacenter -> Floor -> Rack -> UCS FIC -> UCS chassis -> Blade -> Service Profile -> ESXi host -> provider vDC -> org vDC -> vApp -> VM -> Service
or for plain vSphere:
Datacenter -> Floor -> Rack -> UCS FIC -> UCS chassis -> Blade -> Service Profile -> ESXi host -> HA/DRS Cluster -> VM -> Service
My 2c.