I have a friend getting married, she needs a cake to feed 125. What are the different ways I could do a cake to feed 125?

I would prefer not to do anything more then 3 tiers.

Hi, here is wilton serving guide. This one gives servings between 100 - 150.

http://www.wilton.com/cakes/tiered-cakes/serving-amounts-100-150.cfm

HTH.