How would you pack these...
 

I am travelling with a Kinesis Freestyle w/ an Ascent. In other words, it's two halves of a normal keyboard, with some steel plates folded under it. Extremely unwieldy to pack. Especially that the same bag should contain my Samsung LD220G. Steel meet glass inside suitcase == no monitor. Mostly I rely on bubble foam around the monitor, the keyboard in some cardboard box but the cardboard box needs replacement almost every flight, it just gets destroyed. Both halves are about 8x8x2 inches. I have tested the size with a pizza box :)

I have an Eagle Creek Switchback ES25 and an older lightweight Samsonite. I am totally open to buying some new bags if that helps. I love buying bags, sorry :) I am eyeing the Rimowa Limbo anyways :)

Get a couple thin pieces of plywood at the box stores to keep them separate. Cardboard is pretty much useless and as you have said doesn't last at all. You could also pick up a piece of rigid foam insulation to keep them separate for even more protection.