Ok, you asked for it... I have had this planned out, and even drawn up (but not scanned), for a long time now.

Attached garage or extra room, still part of the house but not the bedroom. Fully insulated, and well, including roof and tile floor. There would be at least one electrical outlet on every wall, and recessed LED lighting, since fluorescent messes up my eyes. The room would have its own AC unit and space heaters, which would all be thermostat controlled.

Outermost wall (across from door) will have a walk-in closet for supply storage, a smaller closet incubator, and a 'kitchen' area with large stainless steel sink, large counter top, chest freezer (for FT rodents), mini fridge (for medications etc.), and a 'washing area' like an enclosed tub with hose for spraying down/cleaning.

Left wall (from the door) would be for the lizard cages. My BTS, and Leo Gecko would be there, along with the Chuckwalla I would love to have. Of course, everyone would have nice big custom enclosures. This would also be where the door to the backyard is - leading out to an enclosed 'play/basking' area, the Tortoise Pit (for box turtles or leopard tortoises) and the covered porch where my Iguana enclosure would be.

The Innermost wall (with the door) would have the snake cages. I do not like racks/tubs, so mine would all be housed in stackable display cages or multi-cage single units (like my corns are now). I would have all Herpstat and Johnson stats for the snakes, and there would be a nice cabinet nearby for feeding tongs and other regular necessities.

The right wall would be where the exercise area is - a large enclosed pen where the animals could roam. The entire wall on this side would be a mural, reptile oriented of course. Not sure exactly what, though.

I haven't quite figured out the full size of the room yet, but it wouldn't need to be huge. I know there's probably more as far as details, but it's late and I can't recall them at the moment.