What Long Trek would you want to see?

If this Long Trek format can survive the critical nuking that Section 31, hopefully they can focus on not reworking pilots and just making something that feels like a films.

Personally, while I'm dead certain plenty have had this idea already, I'd like to see one about Sulu on the Excelsior, ideally for the 60th Anniversary. If only because it's a lot of unexplored territory (at least in the current canon), it can be self-contained instead of needing to be stretched out over several seasons, and we still have Takei around for the moment so we might as well make use of him if he's up to it.

How about you? What 90-120 story across the Trek Timeline would you want to get a Long Trek?