Ahhh, this sounds SO nice!!! I have a tall dresser that I have my BigShot on, because I like standing to use it. If I had a plug back there, I'd add my Cricut to make it easy!
For one thing, I would make sure there was nothing but clear space underneath for about 2-3 feet wide so that you can stand comfortably & that your feet don't constantly "bump" something while you are working. That's one thing I would change if I could.
Also, if you're getting custom shelving under it, I'd have a VERY WIDE pull out drawer in the center under the counterspace. I'd put my 12" trimmer in it, as well as my Cricut pads/cutting stuff so that it's easy to access. It wouldn't have to come down very far, just enough room for what you need at that station.
I would also have storage close at hand for Cricut cartridges, dies for your machine and embossing folders. I'm not sure beyond that because I don't know what else you have...but I'd do a huge inventory to see what kind of different spaces I would need. It would be a tremendous help to have some small cubicles for bellies and things and larger ones for tools & such.
But even with the BEST inventory, planning is hard because you never know what you may "need" in a couple of months, right?