Simple drapery panels can not only help a room look finished, they can help a room SOUND finished. I know curtains have a bad rap these days, but don't sell them short. They help you save energy by keeping a room cooler in the summer and warmer in the winter, and they cover those cold black holes that appear in your room at night.
Fabric naturally dampens echoes - and I can't tell you how many new houses I go into that sound like a high school gym. Clap your hands....does your house need drapery?