My 2 cents worth:
First, let me declare that I don't have a darkroom/bathroom (notice the darkroom was listed first) because I have access to a fully equipped darkroom at our local art gallery where I have most of my own equipment (I teach classes there). However, since nothing is for ever, I've been thinking about how I would set up a darkroom in my bathroom, if the need arose. My 2 cents worth are a penny each: (1) Because I'm concerned about my enlarger getting out of alignment from being moved frequently, I thought I would set up a permanent dry side in an adjacent room and use a paper safe to transport the exposed paper to my wet side (read: bathroom). Of course, this would necessitate two safe lights-not a big deal for me. (2) To conserve space in the bathtub, I would stack my trays on vertical shelving with each shelf offset from the one above and work my way down. I could do 16x20 prints and have 5 trays on the go (developer>stop>fix 1>fix 2> hypo). My print washer (I made one that can do 8x10 up to 16x20) would sit at the other end of the tub and be fed by the shower head and drain into the tub. Anyway, that's how I envision it. I'm looking forward to seeing JBrunner's finished project.