I use Story of the World to supplement my weekplans (I have 2 UG students, next year, we'll have 1 LG, 1 UG, and 1 D). I also use Mystery of History audiobooks, but I'm hoping to be able to buy the textbooks next year. We don't use the activities with either, we use the TOG activities. Anything more would be overkill, I think. I could be wrong, I haven't bought next year's yet, but I think Streams of Civilization is what is listed as the alternates for D level.