I think white looks great for a backing. Your top will have lots of white so I think it's great choice. Your quilting will show up great on the back as well the front. I personally like to have the thread match the backing but that's only my choice. You choose what you want, don't listen to someone that may have different tastes than you do.

And the reason great grandma and grandma used white on the back with white backgrounds and pretty reds used for the patchwork or piecing was they wanted to try for a white background throughout the washing life of the quilt! White niot Pink and they didn't have those color catching sheets! rofl Real quilters are too busy figuring out their next design to worry about the unsolicited advice of the quilt police!

Your quilt, your choice

Oh my, the white background has been used throughout history, some to save expences, others to show off the wonderful quilting. So please do use a white backgroung if you wish. I have used lots of prints, as I wish, some to hide my new quilting skills, some for a different look on the back of the quilt. I just was given a hand stitched star quilt with white background made with brighter 50's prints from a friends mom's stash and I plan to use white to add to the quilt. So go for it, remember it's yours and have fun.

Lou,
It is your quilt and you do it the way you want. I have used white on the back of quilts and I feel that I am a 'real' quilter. So go for it. Please post picture of your quilt when finished.