I am a BIG FAN of a double pom pom hat, on anyone from newborns to adults, and when there's a matching cardigan involved I just go nuts. Two cardigans, both double breasted which is a really nice and quite unique touch, along with the hat. This is one hell of a winner from King Cole in my opinion.
We're definitely recommending King Cole Cherished DK for this one, a solid-shade baby yarn with a gorgeously soft handle. However, there are self patterning variants in the King Cole Cherish DK and Cherish Dash DK, which I don't think would detract from the pattern at all.