Stretched Cluster is very famous when you use SVC in a VMware environment.
It allows seamless fail over when any component of a SVC storage environment breaks
The benefit is, that the VMware virtual machines will not stop working.
A former IBM colleague of mine created a very nice foil about this - please use F5 after download to see the animation
SVC Stretched Cluster Animation.pptx
If you want to monitor both, VMware storage Objects with SVC you should have a look here into the VMware integration module for BVQ.