Data centers in a box?

So I've become aware of a growing trend of "Datacenter-in-a-box". Some call them integrated stacks, cloud computing in a block, etc...
Long story short, corporations struggle with different silos within their organization all coming to agreement on products to buy. Some of these DIB's (just coined that acronym.. Use it at free will but make me famous.. I'm narsasitic like that) are able to bring a proven packages from PO to fully integrated in 30 days. We all know of some corporations that get so wrapped up in themselves that it can take 6-9 months to get a new system fully up and running. So let's say you were in upper management and wanted to entertain the idea of one of these solutions. Which one should you pick? Are they all pretty similar or are there vast differences besides just what vendors are involved? I've only researched a few and already pretty lost myself. Generalizations are pretty easy to make, but what really matters is what you are going to be happy with? If you're biased to a particular vendor, the decision is pretty easy as most only offer 1 DIB, with different models depending on how much power you for see needing. These things are very powerfully and somewhat expensive. Keep your big picture in mind and they generally are very cost effective though.
Jason