I am generally ambivalent about reducing use of uncommon rules subsystems. I agree that the exception to this is things like Library of the Lion or Scars of the Third Crusade. That kind of adventure is my absolute favorite to run.
I also really want to see places that we have never gone before on Golarion, places which are not in Avistan. How about all the cool stuff in the Mwangi Expanse and elsewhere in southern Garund? How about some of the more peripheral parts of Tian Xia? How about going into the Hao Jin tapestry again?
I think that a scenario on another planet or related to time travel would be really cool, like the last part of Legacy of the Stonelords.
I am probably in the minority on this but I love genre collisions like with the tech this season or Tian Xia a few years ago and I am really really sick of places like Varesia and Andoran.