Since I bought my conversion bus, my floorplan has changed quite a bit. I found a 1995 International bookmobile based on a 3800 school bus chassis. The sides and roof are flat, square, and tall, so I have a lot of room to build. These are the plans that I'm currently working from. (All images rendered in Google's SketchUp. Fantastic and free.)
Overhead plan view: The driver and passenger seats are on swivels and they can face each other over a removable table top. I've since decided that I will have another section of tabletop in front of the passenger seat so there won't be any banging of feet under the one between the seats. Also, the two seats are on quick-detach pedestals so I can more easily work on the interior during the conversion or when I need to get at the rear half of the engine through the inside cover.
Passenger side. The bookmobile had two doors on the right side. I'm keeping the front door as-is, but the back door will be eliminated when I cut off the sides for the Jeep "garage." I have planned for two chest freezers with one converted to a refrigerator. I also want to have a removable workbench that mounts over the two chests, but I'm still thinking of a way to make it easy enough to move that I don't have to stop whatever I'm doing to get dinner out of the fridge. I've also planned a duct that will channel cold air from the window air conditioner to the various parts of the vehicle—when I'm sleeping I can open a vent over the bed and when I'm awake I can open vents further forward.
Driver side: The shower stall will be where I keep the porta-potty when I'm not taking a shower since it's really a waste of space for more than 23 hours out of every day. I also have wire shelves on the inside of the shower door, but I will use a plastic shower curtain to keep the water in the stall and the hard door will remain open while the shower is in use. Fresh water storage is under the platform in front of the bed wall and it should hold between 180 and 220 gallons, depending on how high I make the step.
What these don't show is the roof deck and access hatch that I just installed. I will have a swing-down ladder attached to the ceiling so I can quickly access the roof deck and whatever additional storage (dry goods, etc) I have up there.