I have the same problem, and haven’t come up with a good solution yet. My wife and I have talked about building floor-to-ceiling stand-alone wooden shelving that can be put along one wall. I saw a photo of a built-in one that had cabinets at the floor level and shelves for portables. The shelves were spaced so that the case tops hung on hooks directly above the portable machines. I think it had two shelves for portables, and hooks in the ceiling for the highest case tops. The shelves were deep enough (width of a cabinet) that the portables and their case tops were displayed setting at an angle. I liked it, but it took a lot of room. Seems like they had track lighting on the ceiling out away from the shelving to spotlight the machines.
CD in Oklahoma