I bought some white plastic channels at Home Depot.
http://www.homedepot.com/webapp/wcs/stores/servlet/ProductDisplay?jspStoreDir=hdus&catalogId=10053&productId=100657480&navFlow=3&keyword=wire+channels&langId=-1&searchRedirect=wire+channels&storeId=10051&endecaDataBean=com.homedepot.sa.el.wc.integration.endeca.EndecaDataBean%408a3757f&ddkey=Search
They come in 5' lengths with various connectors to cover the wire where you link them together. Cheap, effective, and not unsightly. They are backed with adhesive and a peel off strip. The toughest part was snapping the channels closed once the wires were inserted. Of course, the best bet, if possible, is to run the wires through the crawl space above the ceiling.
http://www.homedepot.com/webapp/wcs/stores/servlet/ProductDisplay?jspStoreDir=hdus&catalogId=10053&productId=100657480&navFlow=3&keyword=wire+channels&langId=-1&searchRedirect=wire+channels&storeId=10051&endecaDataBean=com.homedepot.sa.el.wc.integration.endeca.EndecaDataBean%408a3757f&ddkey=Search
They come in 5' lengths with various connectors to cover the wire where you link them together. Cheap, effective, and not unsightly. They are backed with adhesive and a peel off strip. The toughest part was snapping the channels closed once the wires were inserted. Of course, the best bet, if possible, is to run the wires through the crawl space above the ceiling.