A couple that have popped into my head:
1. When resources are required to build something (i.e. Prov house), and I don't have the necessary amount of resources, instead of showing me how many is required in red, how about show me how many I'm short. That way I don't have to cancel the operation, go to my storehouse and check to see how short I am.
2. How about a new general, General Science. This cat would be able to carry all the resources I need for the adventure TO THE ISLAND, and MAKE THEM THERE. No more traveling back and forth unnecessarily.
3. Once again, how about implementing the UI I suggested years ago that lets me assign explorers and geos in a more comprehensive manner? I still have that image somewhere.
4. As already mentioned, a barracks to house gens instead of retrenching them. Let them be kitted out and housed in the barracks.
5. A Foreman character who would record assignments for explorers and geos, essentially stackable orders.
6. Some type of character or something that would let me assign x number of preferred loadouts, such as assigning troops/generals for specific adventures. For instance, we all have our own preferences for advs like Woodcutters. This would let us preset those loadouts, and then with a mouse click or two, loadout the gens and send them off to the slaughters.
That's a few for now.