Botania is a treasure trove of interesting automation challenges.
There is, of course, your standard "Automate the wither" build, which has a decent degree of freedom in how you approach it.
Similarly, coming up with new ways to automate common things, or using mods you don't normally use for something, or even using an unusual combination of mods. Examples: Cobble Works build (your basic materials), tree farm, farm in general. I had particular fun one playthrough using botania for my tree farm (with the bonus of using the leaf eating generator for my mana gen).
If you're willing to add mods, there's an add-on to Embers called Soot, which adds several things (and also changes some things, most notably the ash amounts needed for transmutation though I think there's a way to turn that off). With it, you could automate transmutation recipes. Or you could try figuring out how to automate with existing mods.
Thaumcraft, automating common alchemy recipes.
Basically, look for new stuff or new ways to do stuff, and you should come up with plenty ideas.
