All my machines except for the Cube and the CC are stored in my TV cabinet. Since I don't have a decent CRT for my machines I have repurposed my 40" LCD TV as monitor since it offers VGA connectivity. Kind of overkill for machines which usually just display 640x480 (the 6100/66 DOS Compatible and the Performa 640 DOS Compatible), except for the 7500 which runs at 1024x768. 
The cube sits permanently on my desk near my PC beast, and the CC is floating around depending on my mood - it doesn't have a permanent home yet.
I guess in the end storing/placing your machines will depend on how frequently you plan on using them (if frequent then they should be somewhat accessible). Ideally they should be kept out of direct sunlight and away from artificial lighting in order to prevent any potential yellowing. Also, a less dusty environment can be rather helpful...
~BeniD82
The cube sits permanently on my desk near my PC beast, and the CC is floating around depending on my mood - it doesn't have a permanent home yet.I guess in the end storing/placing your machines will depend on how frequently you plan on using them (if frequent then they should be somewhat accessible). Ideally they should be kept out of direct sunlight and away from artificial lighting in order to prevent any potential yellowing. Also, a less dusty environment can be rather helpful...
~BeniD82