World Imagery Firefly was created for thematic maps.  Currently in beta, Firefly is an alternative view of the default World Imagery basemap, and is designed with desaturated colors.  When zoomed out, the map appears grayscale, but as you zoom in, the colors become more saturated until the full color detail of the imagery appears.  World Imagery Firefly is especially useful for overlays of  brightly styled layers when you want an imagery basemap, but do not want the imagery to compete with the layer styling.  Check it out.