At the suggestion of a friend a few years back, I started adding Provolone to my pizza's and it made a huge difference in the flavor, overall cheesiness, texture, etc. I consider it an absolutely essential ingredient now. Generally all do a layer of provolone and cheddar cheese, various toppings such as ham, pineapple, jalapenos, olives, and mushrooms, a mozzarella cheese layer, and tons of pepperoni topped with Parmesan cheese.