I really like the color palette done with Kill la Kill. Muted and subtle navies and blues, washed out, subdued, then with splashes of crimson all over the place for emphasis and impact.
It's a nice contrast to the usual color schemes in anime, which are a choice between watercolor pastel for gentle/happy series, and intense saturation for action series (Guran Lagan, the closest series to this in spirit, fell into that category.)
Usually when something opts for a darker color scheme, they stick to earth tones. (I'm thinking of the Ruroni Kenshi OVAs - even the blood in that series, and there was a lot of it, was brownish instead of bright red.)