You guys have some great suggestions!
A few things I forgot to mention:
Comfort/Luxury levels - the game equations take luxury levels into account, but its one level for every airplane in the game. I agree that it is a realistic component to an airline, but have to admit that this is being put on the back burner for the time being until we can get a stable environment.
Multiplayer Capable - Right now this game is planned to be ONLY multiplayer capable. AI isn't in the plans yet, but we hope to down the road aways. The game well be able to run entirely solo (with no multiplayer or computer opponents) using the game engine included in the software itself. All multiplayer gaming will be done by the program sending a message to the server to run, along with everybody else's inputs, and an update sent out to each program when they request it.
Labor Disputes - The way we plan on handling labor disputes is strictly with the pilots and compares their wages with other airlines comparable wages. If the pilots wages fall a certain percentage below the average, they will warn of a strike and luxury level will fall due to the poor service. If after a certain time the wages are not brought up to be competitive, the pilots will strike and all airplanes will be grounded.
Cargo - Cargo will be added later, but that requires a completely different engine. Our goal right now is to get a working game in operation and add on from there.
Purchasing aircraft - For every aircraft bought after the first one, there is a 10% reduction in the price. I'm not sure how accurate that is, so some feedback is much appreciated. We also plan on creating an airliner market where you can put old airplanes up for sale, or can buy used airplanes. This will allow startup airlines to have a cheap means for aquiring aircraft. There will also be an aircraft and a certain amount of money given to each airline to start with.
Terminal Fees/Gates - There are a limited number of gates to use at each airport. Dallas Ft. Worth will have plenty, while Washington National will be a battle for each gate. We plan on implementing an auction of some sort for the gates, but haven't started programing that yet. We are also including a way to build your own terminal and rent out extra gates to other airlines. This should add an edge to creating a hub airport.
Feeder services/commuters - The size of an airline's route structure will enhance ticket sales by an undetermined amount. Using this, we can include code-shares where you add both airlines route structure together to create even more revenue. Commuters will emerge during the game as gates at larger cities fill up. This is the flexibility of the game that no other has. You start the game with a different scenario each time, since all of your opponents change. Where one game you might find it profitable to fly 747's from JFK to LHR, the next you may only be able to find gates in Cincinnati and run an RJ empire (be careful of labor disputes though
Starting date/historic events - right now we only have ample information to start the game in 1980 at the earliest. Our priority is to get the game up and running, and then we will research earlier starting years and such. Speaking of which, when the time comes I could really use your help in finding aircraft prices and running costs.
Once again thank you for your suggestions. This game isn't being made to make money, its being made so that we can play it. There is no game like this, and for me to have opponents to play against, I need to make sure you guys will enjoy the game enough to play it. Majority rules, within reason, as to what this game includes.
One more thing...I could use a name for the game. Best I've come up with is "Sky-train"