What kind of desk are y'all using for your montage and computer? Mine is just sitting on a roland z-stand with the computer monitor on a monitor stand directly behind it...and my focal monitors on each side. computer keyboard is sitting on a little table beside me and the mouse is on top of the montage. Not the most elegant setup but it works and it's cheap.
A folding table for my computer, then at a right angle another folding table for my MONTAGE6. I only use headphones and only have one good pair, so using a extension cable I routed the headphone output to the front of the Montage. The time it takes to swap my headphones over and remove my fabric cover is about the time it takes for the Montage to boot up, so it works out well.
I'm sure there's everything from folding tables at your local grocery+goods or Ikea retro-fit to purposed workstation furniture with slide out 88-key shelves, built-in racks, and all the bells and whistles.
I've got something between. I've got "low-grade" workstation furniture for my studio only gear. A Z-stand workstation (with monitor stands, CPU stand built in) for the "L" of my studio-only gear. Then, over the Z-stand workstation, I've got wire rack shelving where I keep the Montage temporarily since it's constantly going back and forth between the studio, practice, and gigs.
But really, you're going to see just about everything that can work under the sun as support furniture for these synths.
Current Yamaha Synthesizers: Montage Classic 7, Motif XF6, S90XS, MO6, EX5R