Voyager‘s design blueprints placed the crew quarters around decks 4 to 8 in the upper saucer section. As on Star Trek: The Next Generation, the art department adopted a modular design which could be adapted as needed for each member of the crew or a ship’s guest on an episode by episode basis.
According to Richard James, “The basic space was permanent but the interior walls had beams across the top and we had channels in there that the walls could go in and out of.”
Each segment we called a ‘bay.’ Because the design was modular, you could give it two bays, three bays, or one bay. How big it was would depend on the importance of the character. Of course, Janeway had, I think, four bays. The beams made niches in the walls and a lot of the furniture could play into those niches and come and go.
Each character had their own furnishing. There were some elements that were the same but we would give everyone something different so the rooms had a personality.
There was another crew quarters set on Stage 9 which did not have windows, implying it was deeper inside the ship. This style of quarters were for junior officers and enlisted crew.
From “Designing the USS Voyager,” Star Trek: The Magazine 1, 19 (November 2000)