Of the two, I would use the cream. But I'm using a similar (but MUCH smaller) palette for my Fiesta quilt and the black background is absolutely gorgeous.
http://www.fatcatpatterns.com/Fiesta.html
If you really don't like black, I would find the darkest gray in one of the batiks and go a little bit darker in value than that darkest gray - either a dull Navy, dull brown, dull green, but a very dark shade of whatever color you choose, so that the darkest gray doesn't fade into the background.
A dull, dark color can be beautiful - those applique fabrics will really shine and sparkle when the background isn't competing for attention.
