There are a lot of good resources.  We currently use TAN's The Story of Civilization, but that is probably a bit "much" for the earlier grades.   One thing I would remind everyone, is that Americans can fall into the trap of thinking that "American history is the only history".  We study the history of the whole world, and not just Western civilizations --- we looked at the Aztecs and the story of Moctezuma and Cortes just the other day.  Our curriculum is deliberately Eurocentric, partly because my son is a dual EU/US citizen, partly to counter the trend of modern American secular society that has called out white European civilization, and its male aspect in particular, as something to be hated, shunned, and forgotten about.  (That said, we have zero tolerance for racism, and we proactively study civil rights themes as well.  When we were on vacation this summer, one afternoon I took him to a formerly segregated beach village, which still bears physical reminders of that era, and we discussed what our vacation would look like if we were black and living in the 1950s.)