One example of when I "did my own thing" was when the week before trek I gave a history lesson on the migration and settlement of the great basin by the pioneers including a timeline of migration periods (handcarts were short lived), where the pioneers came from (mostly the NE US and northern Europe), the raw numbers of how people arrived (most came by train), and BY quotes about the handcart experiment (he considered it mostly a failure, hence the focus on building the RR). I figured some context was important before they went.
I've also done lessons on atonement theory, the structure and origin of the Bible and an overview of other faiths' beliefs. Each of these lessons was in response to a question from one of the youth. When I have gone off manual in cases like these I have found the kids to be highly engaged. They are eager and ready to learn, but too often we spoon feed them the same mush we fed them in primary.
Anyway, I'm currently callingless at this point so I can't drag anyone down the slope with me right now. Better enjoy it while I can.