It looks really nice as it is but if you did add the extra background quilting it would really make the applique POP off the background!!I guess it all depends on the look your client prefers.
I love it just as you've left it, but I would probably love it filled in, too!
I like it like this.
Love it just the way it is!
I think some pebbles or a very small stipple would look very nice in the background. Really make the applique stand out. Lovely quilt. I love what you've done so far.
That is an adorable quilt and your quilting looks great on it. I am sure whatever you decide will work out perfectly.