First, let me say that I shouldn't be on the Board before my caffeine. I thought your subject was "to stash or not to stash" and I thought that was a ridiculous question. Who wouldn't want a stash?!
LOVE your blocks and the fabrics that you have chosen What a happy quilt!
My two cents worth - I'd get rid of the plain blocks and replace them with another block of the prints that you have used (I love them!). I'd do a narrow sash in black. Just make sure that the blocks that are all one fabric are dispersed throughout the quilt and not clumped in one area.
I'm anxious to see the finished product. It's gonna be fabulous!