I LOVE a pieced back!! I have only done one solid backed quilt and that is because I knew that the person who was getting it (MIL) would never use and it would be laid across the back of her couch. 2 years later, it's still there!! She got a little touchy when I used it last Christmas when I was cold and pulled it around me. Her quilt, her rules I guess!
The back is just another place to add some more color or another element to the quilt. I am on a roll with baby quilts and I make up extra of the blocks I use on the front and put them on the back. A lot of the time, I just use 2 different fabrics and split up the back.