This is basically my pizza page. With pizza sauce, there are four principal directions. (Click here for pizza dough.)
This is very un-American, but in Italy, pizza is a bit of a regional thing. Each region has its own practices and there are those that don't put so much of a sauce as just olive oil and/or toppings. I'm not particularly conversant here, but this is what I've observed.
Oh, my. You haven't had pizza until you've tried it with pesto sauce topped with thin slices of fresh mozzarella and thin slices of Roma tomatoes plus maybe some whole, fresh leaves of basil. The first time I made this, I nearly fainted it was so good. My wife did too only to find out several minutes later that she was at risk of dying from anaphylaxis: she's discovered she's allergic to pine nuts.
All my recipes have their own sauces made from tomato because, after all, it ain't pizza unless a) it's got tomato-based pizza sauce and b) no pineapple on it.
Ensure the alfredo is not too thick and rich or it will overwhelm the toppings. Cubed chicken and garlic go well as toppings. So do spinach, artichoke and asparagus.
There is little sense in going too far here; everyone has his or her own ideas anyway. I'm just going to list my favorites here and add two un-favorites.