I'm getting ready to purchase a cake plateau, one of the big silver ones. I'm planning on renting it out. I need it to at least fit a 16" cake but I'm trying to decide if I should get a set of them (much more expensive) or if I should just get an 18" one. Any words of advice? And does it look better to put a square cake on a round stand or a round cake on a square stand?

I'd put a 16" cake on a 20" plateau. What's wrong with putting a round cake on a round stand, and a square cake on a square stand?

I'm hoping nothing is wrong with putting different shapes on. I don't want to buy a set of round and square ones!