I've made this cake a couple of times. Using the 6" and 8" double layer rounds, you should get 36 servings according to Earlenes cake cutting chart. I have also made it using 8" and 10" double layer rounds which served 60. I would not recommend going any bigger than that as it might look strange. If you need it even larger you could do the 6" and 8" castle and add a 10" at the bottom decorated to look like a field of grass and add some flowers. I hope this helped, good luck!
10/3/11 at 10:22pm