Before writing any of the Astronomicon novels, I like to plan out the locations in great detail. It not only makes life easier for me during the writing, and improves continuity, but also throws up a lot of ideas which I might not otherwise think of. This can lead to some interesting ways of using the scenery.
Years ago I did this planning on paper, but technology has moved on for all of us and now I use Sketchup to throw together the layouts and designs. Below are a couple of example views from the designs for the setting of the latest Astronomicon novel. These show the passenger deck of interplanetary freighter Celtic Conveyor.
The undecorated area to the left of the first picture is the cabins area. The bridge and administration areas will be on the deck above. There are two lower decks below the passenger level. The upper one contains the crew quarters, stores and service areas (laundry, wastemanagement etc.) and the lower one houses most of the automated systems such as air processing.