Those blocks are FABULOUS!!! Contemporary Amish. LOVE it.
As for the back, it's a personal decision.
Me? I'd use some fabulous loud print. Like a Kaffe fabric.
Just as a really quick example because I have to run, put "teal" in the search box here:
http://www.gloriouscolor.com/store.php?cat=126
I'd go for the second one, with the huge teal and red flowers. But there are other more "subdued" ;-) ones. Or something like that in your LQS.
I mean, you've already shown that you like teal and black on the front of the quilt. And you've got plenty of clean, straight lines in those blocks. Why repeat that on the back?
I think a quilt definitely benefits from and needs having something (totally) different on the back.
Think of the furniture in your living room. Your couch is a striped fabric. Are you also going to make the pillows from striped fabric? No, you're going to choose coordinating/complimentary colors, but in another pattern. Otherwise, it's just so bland.
Again, it's a very personal choice. :mrgreen: