So the one thing you need to be aware of, is that you don't control Shadow Copies ... these are a vCenter mechanism to transfer Lined Clone chains between datastores.
For the purposes of vCloud Director, you place your Templates (Catalog Items) onto a Storage profile within an Organization vDC. They will live there until something changes.
your Org vDC also has two settings:
1. Thin Provisioning
This determines that any BRAND new VM created in this OvDC will use a Thin provisioned disk by default when created, or the disk produced by the 'consolidate' feature will be thin provisioned.
2. Fast Provisioning
Will any copy be a full VM (off) or a linked Clone (on)?
Once the above two decisions are made, the only thing you can control is what storage profile the VMs are assigned to. Then vCloud Director and vCenter handle the rest.
If you are running vCenter 5.1 + ESXi 5.1 + newest version of VMFS, you can also use Storage DRS with Linked Clone chains to assist in load balancing. Just make sure your storage clusters directly correspond to the storage profiles in vCloud Director. you don't want storage DRS moving a VM to a datastore outside the storage profile.