I read everything Heinlein wrote right up to about 1971. His books after that didn't do much for me. It seems like the mainstream success of the overrated 'Stranger in a Strange Land' sent him off in a direction I couldn't get into.
After 'Stranger' he sort of went off the deep end. I recently reread most of his old stuff and 'The moon is a harsh mistress' is still my favorite.