The only thing I have never done is the attraction that opened up less than a month after my last trip ended: Mickey and Minnie's Runaway Railroad.
We have an app that we like to use to keep track of what all we do each day when we visit the parks. In 2017, which was my first ever week-long Disney vacation (after a lifetime of a day here or there or a long weekend), we set out to do each attraction at least once during the trip: rides, shows, and movies. We ended up not accomplishing that goal because our trip got cut short by a day and a half thanks to a hurricane (Irma maybe?). In 2018 when we returned for another week-long trip to close out that AP, we hit all the stuff we missed the year before, plus riding the new stuff in Toy Story Land. On trips this past fall and early winter we managed to ride the new Star Wars stuff and see the new movies in Epcot, catching us up. So all that is left is MMRR in Hollywood Studios.