Next year graduation party?

ok so i know its early,but i wanna start to plan now. My parents seem to think hotdogs/hamburgers/sloppy joes.and i think YUCK! I am going to buy the food myself. I was thinking about KFC or Pizza Hut. I want to have good food ya know? i was thinking probably 100-150 guests to invite. So 170 pieces pf chicken,5 gallons of potatoes&gravy. or like 40 pizzas? idk help!?