One of the most crowd-pleasing birthday cakes I made for my daughter came from the Disney Family Fun book. It was a Sleepover Cake made by cutting Twinkies in half the long way and placing them atop a sheet cake, before frosting the whole thing to look like one big bed. Each Twinkie-shaped girl then gets a Nilla-wafer head and squeezed-frosting hair. We decorated the bed's blanket with frosting flowers and gave each girl a designated guest's correct hair and eye color. The cake was a huge hit and pretty easy to make. There's a picture of one here:
Let us know what you end up making!