My favorite potatoes to serve with BBQ are twice baked potatoes. Just bake the potatoes and let them cool. Then cut them in half and scoop out the insides (a spoon works well) and put them into a bowl. Mash the insides of the potato corsely and add sour cream, cheese, onions and meat, if desired. Then put the mixture back into the skins and bake until the cheese is melted.
I usually add whatever kind of cheese I have on hand, like cheddar, monteray jack and parmesean. The meat I like to add is either bacon, ham or canadian bacon.