I think that there should be different costs for gates at an airport.
- One cost to rent a gate
- One cost to rent a plane stand
- One cost for a landing slot (one arrival and one departure)
Separate or a different option would be gate costs for different size aircraft. I mainly think about this when expanding my terminal buildings. Having a main terminal and a commuter terminal.
A new fee structure for gate usage could add another aspect to the game.