It would be cool to see one of the many empires in Trek actually expand their empire by conquering another race's planet and civilization. It seems that's what an interstellar empire would do -- physically conquer worlds and peoples by force to expand their imperial outreach.
The Klingons launching a large-scale planetary invasion of some outmatched civilization would be sweet.
It could come early in the film, provide them with some badassery, and show the Klings in glorious expansionist victory on-screen. That would help build up the anticipation for the later showdown with Our Heroes.
It wouldn't even have to be that long, but it could be big.