You could make an enormous desk from a piece of kitchen worktop and some of those worktop legs. That's what I'd do, if I was starting over; but for now this is what I have.
A cheap plastic shelving unit which fitted the available space. That monitor on top is a Sun unit with a Trinitron tube, so it is very heavy.
The "console" computers live on an Ikea Billy bookshelf with added shelves. This is a good solution, but you have to keep the power supplies, cables and other paraphernalia in a separate box.
These plastic boxes are labelled (mostly) and store the aforementioned paraphernalia. The idea was to be able to pull the console and its box of bits and assemble the thing on the desk, as and when. Then return all to storage after playing. Of course, it never works out like that! The shelves are Ikea and they also carry manuals and books for all the computers.
The really heavy items (PET 2001-N, PCW9512, TRS-80 Model IV, Model II, Sharp MZ-80A, Exidy Sorcerer and an extremely heavy Audio Innovations Series 500 valve amp) sit on a steel framed unit such as you would find in a garage or workshop.
This is the desk; it's an Ikea unit with extension that I bought second hand. Of course, it's not big enough, especially with that SuperBrain. There's a drawer unit to the left, out of shot, that is stuffed full of cables and other detritus. On top of that is a "tweener" PC. Above the desk there is a shelf which has the desoldering station, 'scope, a stereo for music and a seldom used 24 pin dot matrix printer. There are a bunch of machines under the desk, too - A couple of Power Macs, TRS-80 Model 4P, Philips P2000C, Sun Ultra 10.
Reading the thread, I am pleased to note that I am not alone when it comes to chaotic "retro" work spaces. Seems to me there is just too much junk that comes with these machines, and no perfect method to store them in a way that allows for tidy display and easy access. Unfortunately for me, I have to use this space for real work and so I cannot afford to leave the desk cluttered with retro computers. The other thing is that I have very little time to play with the old machinery, and so it is more of a museum now. I have over acquired, that's for sure, but can I bring myself to start selling?