My law for Si coziness is: warm colors and lighting, needs cushions and soft surfaces. Dark green, red, brown and yellow are always cozy Space needs both room to pace around and close distances alike, if it's too wide with no decoration it's boring, too clinical. Things that are ultra bright are off-putting in relaxed parts of the house, esp. the bedroom. Curtains and many fabrics can make it exciting, usually. I found a good representation of that: