Pastel or softer colors look better in flat paint. Chocolate brown or very dark colors, I think look better with a little shine to them. The satin or semi finish will keep them from looking dreary by reflecting light around the room. Painting is the most cost effective way to give your room lots of impact. You may want to select a striking wallpaper pattern in keeping with the color scheme of the rest of the home. Stripes are great for adding volume and height.
In a small foyer maximize the light and make a tight area feel less cramped with a floor to ceiling mirror. Your foyer may be a tiny space with only a coat closet and no place to hang a mirror. So why not mirror the closet door! This will make your space appear larger. Depending on how your closet door is positioned, it may double a gorgeous view of the outdoors.