A Margherita is my favorite, but here are some of my other personal favorites:
1) Fresh Mozz, Brussels sprouts, pancetta, sliced garlic, parm, evoo
2) Fresh Mozz, sliced cremini mushrooms (raw), parm, black pepper, and white truffle oil post-bake.
2) Mascarpone + blue cheese (about 3:1), thinly sliced asparagus, post bake: Meyer lemon evoo or evoo, fresh lemon juice, salt
4) Fresh Mozz, dried cherries plumped in brandy, hot fennel sausage, red pepper flakes, local wildflower honey and fresh basil post-bake
6) Tomato (by which I mean tomato sauce like you would put on a Margherita), fresh mozz, sopressata, sliced garlic,red pepper flakes, and fresh oregano
7) Mascarpone, cherry tomato, post bake: prosciutto, arugula dressed with evoo, lemon juice, salt and pepper, and parm
8] Tomato, good anchovies, black olives like kalamata, red peper flakes, Calabrian chili oil or evoo post-bake
9) Tomato, fresh mozz, roasted red onion slices, roasted mushroom slices, and prosciutto added post bake.
You’ll find pictures of all these and others starting about here: http://www.pizzamaking.com/forum/index.php/topic,14249.msg182811.html#msg182811
and going forwards.
Good luck with your party. Please post pictures of your pies!