Honestly, about 4 plates which usually have pasta, shrimp, Alaskan king crab legs, prime rib, etc. Usually no salads, soups, fruits or anything healthy. Then about 2 or more plates of dessert, always getting the crêpes and several dishes of crème brûlée as well.
Whenever I'm visiting friends in CA, we usually eat at Choices, The Buffet at Pala Casino and we see who can eat the most.
Sure my friends and I feel horrible afterwards, but to us, that's the whole point of eating at a buffet.