Just a PSA from a dairy-free mama. First of all, you are such a kind friend to think of adjusting the menu this way. I guarantee all your friends will be thrilled to walk into a whole room full of food they can eat.
Second, just make sure to double-check the ingredients list on anything store-bought -- English muffins, for example, have milk in them. Other muffins might be made with butter. Even many margarines, which people naturally think of as a dairy-free sub for butter, actually contain some milk. WF sells a reasonably good df cream cheese, if you want to throw some bagels into the mix.