a train could easily be girly if you changed the colors on there - lots of pinks and purples, carriages with girly colored lollies...

the cupcake rainbow sounds cool too! and you could get the gold chocolate coins for the pots of gold... though you'd have to do either a really big cake, or really little cupcakes to make the shape work...

good luck - i love the sounds of lady bugs - ae you having a them for Izzy's birthday party - or are you planning the theme around the cake?