for high school I did different things for different kids
I did some of Spievogel Western Civilization. I really liked this - I was more enthusiastic about this than my children I have to say
I tried SWB history of the world books, but they didn't work for us
the main thing I did was make a reading list of The Great Books - 8 books a year I think that tied into both the history year that we were up to and their interests sort of. So Oldest DS did science or math great books etc.
By year 10ish, we changed over to either Open University units or TAFE courses