Very much in agreement on Thanksgiving and Halloween, even though we've widely managed to turn that into about the food. In our family, we've done some things here and there over the years to bring out the "Thanks" part, but I'm not sure we can call it a tradition. Maybe we can come up with something for the grand kids.
Halloween is just an odd thing to me. As you say, celebrating the bad and the ugly, which is probably putting it mildly. But since it's watered down and aimed to the kids, it's okay. Doesn't make sense.