Original Layout: I get the feeling that the toilet was in its own closet. That the clawfoot tub was in its own room with a sink or two? All our bedrooms have old plumbing lines from sinks in each closet.
As Purchased: When we purchased the house we had two bathrooms squeezed together. The "pink bath" was tight and not very useful. The toilet was tight to the sink, and the bathtub turned out to be a clawfoot, which explains why it felt high/ tall in the space. There was no mirror in this bathroom, either - Just a blank patch on the wall from where it was taken before we moved in. The "pass thru" space had no lighting, no electrical and acted as a private entry to the sunporch. In pictures from the former occupants, the sunporch was a rented bedroom! It has no heat!! Did the mention that the pass thru walls were not even screwed down? You could push on the wall that adjoined the pink bath and it would "wow".
Current: You can see how we left the plumbing for both the toilets and shower in place, and incorporated the pass through as part of the Master Bathroom. The sunporch, in turn, turned into our own private suite. Right now we have misc. furniture out there acting as a mini office. We use a space heater to keep warm in the winter. The vision involves some book cases and a built-in desk, a place to make coffee in the mornings and a comfy chair for weekends.