[libvirt-users] Virtualization Management Platforms

Hey All, Curious about the best, easy to use virtualization management platform for small labs of 30-40 physical servers. Looking for something that's relatively simple to operate, install and lightweight but with enough maturity to provide monitoring as well as holistic views of the entire physical space etc. Hearing of oVirt, Xen and Eucalyptus to name a few but wondering what other options do I have for a small physical space? -- Cheers, Tom K.