This brown outline is my favorite with a real retro feel, and I'm fairly certain that's where we're going with this. Need to keep in mind, though, that the other last duck cards have different accent colors.
This gray outline is great with the blue, classic, almost cartoon-y, but falls a little flat with some of the other colors (black, orange, pink).
Colorful blue on blue is fun and is what I chose for our holiday cards. But I think maybe not for the series as it means two separate colors for each of the eight cards.
