I settled on half chocolate cupcakes and half vanilla. I also settled on half chocolate frosting and half vanilla. So in the end I had: 12 chocolate cupcakes with chocolate frosting, 12 chocolate cupcakes with white frosting, 12 white cupcakes with chocolate frosting, and 12 white cupcakes with white frosting. I nice variety, I think.
I also had 16 truck toothpicks, 16 flower toothpicks, and 16 heart toothpicks. So after baking and frosting the cupcakes, I decided to decorate them according to the toothpick themes; trucks, flowers, and hearts.
Orange buttercream piped with an upside-down basket weave tip in four straight lines, two long and two short. Chocolate fudge frosting piped with an open round tip for tires.
Flowers: Chocolate fudge frosting piped with an open round tip for centers. Blue Buttercream piped with an open round tip in five circles for petals.
Hearts: Pink buttercream piped with an open round tip in two halves.
Here they are with the decorative toothpicks.