If I carry anything, I will prefer to carry a dutch oven and a cast iron grill grate. I do understand that not everyone will want to carry that much weight though. But between the two, I can cook a lot of things.
I did get a free Weber (I think it was Weber) grill that folds up. Maybe 12 inches around. The wife has taken it to the beach a few times and enjoyed it.
It has been a long time since we went camping because the kids have grown and moved away but our favorite portable grill was a cheap little hibachi. It was a small but strudy little grill and we could use either wood coals from the fire or charcoal. Like shaun, we also used to use the underground method. We would wrap tightly in foil a seasoned hamburger patty, sliced potatoes and onions and cook them in the underground oven for 30-45 minutes. These are simple to make and delicious!
I'd have to say that if I was going to use charcoal or wood, I'd go with the plain old Hibachi. I don't know how many of these we went through before gas grills became so popular. They're small, cheap and portable so that makes them a good choice for camping.
If I am just going camping and it is in an area where the desired wood is all around I do not take a grill. I build a fire pit and the only thing I bring for that occasion is a grill from an old stove I kept for just such an occasion. If I wanted to do a home style BBQ I would stay at home and use the BBQ grill plus I don't want to carry more than is needed when nature provides what I need with the exception of the grill.