I love print fabric. And all white would be boring for me. I usually will go into the LQS, go to the $5/yard section, and buy a backing when my quilt is ready to be backed. I used to buy in advance but I have some still waiting... so I only spend when I have the quilt ready to go. I pick something nice and close, but since I'm in the "clearance" section, I'm not going to agonize about a perfect match.
I was once there when a lady spent 30 minutes picking out a back. I understand doing that for borders and colors in general, but the back, IMO, doesn't need to perfectly match the front. Shrug.