Hello,
I suggest to make graphs more flexible. In current versions is possible to create graphs either normal or stacked. Would be really useful to rewrite graphs a bit:

1. Every added item in stacked graph should have a checkbox called Stacked. If you select it,then item will be stacked else will be independent.
2. The independent item presented like line should be always visible over stacked items.
This should allow you to create stacked graphs for example: Stacked memory used by VM,Stacked memory provisioned to VM,Stacked Memory operating reserve,Independent line for Memory phys. size.See attachment,please.

I hope,that I've explained it clearly. Current graphs are quite restricted, I think that this suggestion doesn't take much time to enrich them.
Thank you
Tom