I have really grown attached to the idea of "two sided" quilts, and/or more action on the back. The way I work I usually have a few orphan blocks or fabrics that didn't make it into the top (usually because of a large scale print) and more and more I've been incorporating those into the back.
Some of my backs are pretty wild, because they were bought at the thrift store mostly because they were big enough... but it's a great place to use wild fabrics and large scale prints.
I'm also trying really hard to use up stash, and "pieces big enough for backs" is not my strong point. I do, however, have a lot of 3-yard pieces where I can piece two of those into back.
For your quilt, I'd be looking at something with maybe a white background and something swirly (paisley? flower outlines?? butterflies??) in blues and aqua and teal. Or could could go with geometric designs.