Coffee and hot chocolate bar

I can’t decide on how to lay things out. I am having disposable coffee cups for the hot chocolate and coffee bars. Should I put a few creamer and sugar packs into the cups for the coffee and put a pack of mini marshmallows into the cocoa cups OR should I lay everything out for everybody to get as much of whatever they want? I will be having about 60 guest and don’t want to run out or buy too much of everything.