A couple thoughts I think are cool (trains, gondolas, spirituality and districts)
My first thought it expanding on districts. I love the game so far but I think that it would be cool to add more focus on districts.
Idea 1: Give the iron teeth trains. Trains can have a certain number of cars, let's say... three cars. Each car can be the equivalent of a medium storage, 180 logs for example. You build trains stations which haulers/builders can call the train to and transport large amounts of goods too. As well as have the ability to manually stop/move the trains.
Idea 2: Give the Folktails gondolas. Similar idea to trains except the run on line Similar to the zip lines and they move faster but with lower capacity. Single cart with 250 piece capacity.
Idea 3: a third faction that focuses on family and wellbeing. Make wellbeing a more involved aspect of the game. Im imaging a faction based on the Iroquois first nations. Their buildings would be larger and not stackable(3x5 for a basic house) but able to house let's say 12 beavers. Like an Iroquois longhouse.