oh always more ckaes than guests...especially if there are any children around.

My usual rule of thumb is 2:1 - 2 cakes to 1 guests. People like cake, they want to eat more than one most often.
ALWAYS more cakes than guests.

Also, make them from scratch if you can, taste better, and freeze them. Ice them frozen on the morning and they will be thawed by the time you need them

Good Luck!