Another option is using wall decals which can be cute but you have to be careful because they can cheapen the look of the room.
I personally love wallpaper. Here are some of my favorite wallpaper designers and some of their work...
Not only does Eskayel produce beautifully handmade wallpaper, their fabrics are just as fabulous.
Trove could possibly make THE most unbelievable wallcovering. I would love to have this paper anywhere in my home, however, it is quite pricey. If you do fall in love with it though, you can choose one wall in a room and this paper will certainly be an amazing focal point.
Treet - White