In my first paintings, I did not want to cover the whole surface - partly because I didn't want to use up too much paint before my students got at it:) I am thinking of making some of the white spaces in the first sample little creatures. In the second I may simply paint the white areas a dark blue colour. I simulated that in Photoshop in the third image. Other creative potential: see what you see in your piece and enhance that image, or simply overpaint an image that resonates for you onto the painting.
Below are some lovely paintings from various artists.