If I have 12 LUNS that are all the same characteristics, would it make sense to create a Storage DRS cluster containing all 12 LUNS?
Are all LUNs connected to the same hosts/clusters? If yes, then it absolutely makes sense to enable SDRS. (While it's not a requirement, I prefer to map SDRS clusters to host clusters.)
Review this guide on SDRS for more details:
http://www.vmware.com/files/pdf/vmw-vsphr-5-1-stor-drs-uslet-101-web.pdf