Mechanics, features ideas
The best way to explain the depth of the game to the player and to see that it's real (as opposed to a nebulous feeling I get when I don't understand the exact relation between the choices I make the the effect, like in SimCity), there will be a button to calculate the estimated cost of construction for a building with a breakdown of all the costs. It will show all the paths and which trucks will transport the good, estimated completion time based on current set construction wages, the resource prices at the suppliers, etc. This will require a tree-view GUI. Maybe customizing which suppliers or transporters are employed is also necessary, for strategies of minimizing construction time or buying only from allies. Earlier I also had the idea of 'suggestions' of what businesses are in demand and where, kind of like if the AI was giving the human player advice on what it would do.
Second thought: the whole appeal of the economics game to me was fascination with emergent, adaptive systems, like the brain or cells. Obviously this is not possible if the economy is so fragile that it collapses and every worker dies from starvation if the players don't play exactly the right way. So the AI must be robust and step in to balance the economy when the players fail, in the spirit of the invisible hand of supply and demand, in the pursuit of profits.
Third idea: players will make a lot of mistakes and get frustrated, maybe even after playing the tutorial I'm going to include. To help in multiplayer games, players will get three saves points to reuse at any point in the game, to rewind the game in case a stalemate results and all the workers die. This might be annoying if the losing player decides to rewind each time until the winning player just gets tired. So the host should be able to adjust the number of save points before the game starts.
Back to the first idea, workers should also have stats and history data associated that the players should be able to see. The game can be paused even in multiplayer by any of the players, like the SimCity sim speed controller, to evaluate choices and examine the situation. Players should be able to examine a worker and see if his situation is unsustainable or something, if at this rate he's not going to be able to get enough food or rest to survive. And it's necessary to pause to estimate construction costs because all possible combinations of transporters and suppliers must be examined, which requires pathfinding, which is computationally expensive. The calculation doesn't take everything into consideration though, so there is room for the players to come up with better strategies and use their smarts.