On the tiered cakes, i see wires being used holding decorations like stars and balls made with fondant, i am guessing, but what type of wire is that, because i tried the green floral wire and it fell over.
There has been a forum running a lot of this past week discussing NOT placing wires directly into cakes because they are not food safe. Jewelry wire was discussed as an alternative. As well, placing a small drink stirrer-type straw into the cake, inserting wire and then anchoring that with royal icing helps to keep wires from wanting to swing around on a cake. With floral wire, the larger the gauge number, the smaller/ more flexible the actual wire, so you want a smaller number gauge for a more stable wire. I'll try to find the link to the above mentioned.
Here's the topic regarding wire in cakes: