In general, light colors add a feeling of spaciousness. In particular, striped wallcoverings are a sure bet for adding height to a room. Stripes visually raise the height of the ceiling by drawing the eye upward.
At the same time, pastel colors broaden the room, and make the expanse of the wall seem larger. Together, subtle stripes and pastel colors can make a room seem bigger overall by drawing the eye both upward and sideways.