There is lots of room for your own interpretation in this recipe. Use whatever shape pasta you like or have on hand. I usually choose elbow or penne. Same with the cheese. I like equal parts Sharp Cheddar, Medium Cheddar and Gruyere. But you can choose any good melting cheese, all one kind or a mix.
Breadcrumbs: I often use store-bought Panko for breadcrumbs but really making your own is a cinch and definitely tastes better. For 2 cups crumbs take about 3 slices of white or whole wheat bread, tear it into large pieces and put it the bowl of a food processor. Pulse the food processor for about 10 or 12 pulses until the breadcrumbs are the right consistency. That's it. Save any extra in a zip lock bag or airtight container in the fridge or freezer.
This mac and cheese can be made a day in advance and reheated, covered in foil, in a 350 degree oven. It can also hold quite a while. Covered tightly with foil let it rest in a warm oven for as much as an hour until you need it. This is an incredibly forgiving dish, thank goodness.