I never make it the same twice, personally. But I find that we prefer it when we use a blend of cheeses. Usually at least 4, but sometimes as many as a dozen. A mix of sharp and mild, dry and soft. Cheeses like cream cheese or blue cheese are great additions, but only take a very small amount. I love flavored cheeses, like mustard seed or onion/chive/garlic.
Basically I make a white sauce with a basic roux, 2 c of half & half, and about 4 cups of shredded cheese (not packed), a little garlic powder, salt and pepper. Toss that with a pound of cooked penne (slightly undercooked), put into a 9x13 pan, and bake at 350 for about 40 minutes, or until browning on top. You can sprinkle some shredded cheese or some panko on top before baking for a little extra texture. And I usually stir in some meat and veg before baking (peas and sausage are the normal ones here, but I've even done shredded goose or broccoli).