Spaceships are a peculiar thing; as are the Humies - the hardy folks working and living inside these hunks of metal for weeks or months at a time. Ironically in space living-space is at a premium. Any places inhabited for amounts of time need to be oxygenated, ventilated and shielded from radiation - even the hardiest meatbags are pushovers when it comes to environmental conditions.
Thus spaceships were forced to become the marvels of spatial use that they are today, reducing down-times wherever possible:
- Sharing bunks between shifts, or using them for storage
- Having the mess serve double duty as meeting-/working-space
- Using the 3-dimensional geometry by moving appliances to ceilings and walls (e.g. have the cooking area of the mess opposite of the seating area)
- Combining an observation room/cupola with hydroponics
While these conditions mean near-optimal space-usage, they also mean less privacy and ways to escape each other during the weeks or months spent aboard ships.
Q: Where on my spaceship can I justify creating & maintaining these expensive living conditions, allowing me to expand available crew-space as a by-product?
Addendum: Trying to address all points raised in the comments.
Data on ships:
- Travelling between astronomical- as well as man-made-objects in the solar system
- Trips taking anything from a few days, to weeks, to months at a time
- Transporting anything that could possibly be needed to be transported between two, or more, points in space
- Crewed by usually 2 to 6 people, but sometimes more, sometimes less
- Crews rosters are, as with current-day spacecraft, intended to provide a varied set of skills necessary to facilitate spaceflight, as well as facilitate a redundancy of the availability of such skills among the crew
If the given data does not seem sufficient for any part of your answer, please assume a near-future society and extrapolate sensibly. Also consider looking at the linked questions & articles, they're not just there because I like coloured text.