Sheen is about more than shine. Flatter finishes hide surface flaws but are harder to wipe clean; glossier finishes stand up to scrubbing but show every patch and bump. The right choice depends on the room and the condition of the walls.
Ceilings are almost always flat. They don't get touched, and a flat finish hides the seams and imperfections that light picks up across a ceiling. Living rooms and bedrooms usually do well with eggshell, which has a little more durability than flat while still being forgiving on older plaster and drywall.
Kitchens, bathrooms, hallways, and kids' rooms benefit from satin, which handles moisture and regular cleaning better. Trim, doors, and stair rails take the most contact, so semi-gloss is the usual choice there; it's tough, easy to wipe, and gives a crisp line against the walls.
Older homes with wavy plaster or many patched areas often look best one step flatter than you'd expect. If you're not sure, try sample patches on the actual wall and look at them at different times of day before deciding.