We are painting a bedroom a color called Pewter and I am interested in painting a broad, light color stripe across the middle of the room, but I’m unsure if this will make the room look smaller than it already is.
The addition of a lighter stripe could make the room appear smaller by defining its dimensions against the darker background color.
Another way to use the lighter colored stripe is to move it to the top of the wall and paint the ceiling the same color. This would provide a unique effect that might "lift" the ceiling.
Or the darker Pewter color could be used on the lower part of the wall and the lighter color to the ceiling. The darker paint color would appear as a wainscot. These are just a couple of ways to use the lighter color and change the perceived dimensions of the room.
A single broad stripe of light colored paint across the middle of all walls in a room will make the room look definitely bigger, since it will give an effect of partitions made in the room and therefore one room will look something like a hall. Especially if you go for Fabric Color Match of Kravet Couture Oxford Stripe Golden Pewter 22177-116 the finish should come out well. But I think your idea will work out well with a bedroom with large dimensions.