A new studio desk:
The cavity underneath will hold my Fantom FA76 controller keyboard. When I'm not playing keys, I'll cover it up with the removable section of the desktop. I'll use dowels or pins of some kind along the back edge to support the back edge.
Each rack bay should have enough room for 5 units. I'll put audio rack gear in the left side (Echo Layla, patchbay, and the GSP21), and MIDI on the right (D-550, TR-Rack, MIDI Patchbay, and master power strip.
The PC monitor and keyboard will fit between the two equipment bays, and I'll mount the studio monitors on top (sitting on Auralex isolation pads, of course).
I will probably need a separate stand the Roland SPD-20 Octopad. Right now it is sitting on my second office desk, and although moving the Fantom into the desk will free up a tier on my keyboard stand, I'm not sure the SPD-20 will fit securely. Some more thought is required there.
The panels will fall out nicely from a couple of 4x8 ACX Plywood sheets, giving me plenty of scrap for, oh, a drawer on the right, perhaps.