I would use it as the backing to a top of your liking. That way it would be reversible. Lot of other good ideas posted too.

I have been reading about "modern quilts" and I think this classifies as one. I think that is how they originated thru the Amish.

I would make a front, and use that for the back.

A plain muslin or solid black back would be, to me, the best choice for a "plain" quilt. The Amish are the Plain Folk, after all. I use muslin/black backs almost all the time - and no one has ever com"plain"ed. What this baby needs is lots and lots of hand quilting IMHO. The blocks would appreciate it! Then again, I love to have those big spaces to hand quilt. If it isn't your thing - ask the next person.