Microsoft's Flight Simulator X provides a detailed and realistic recreation of what it would actually be like to fly a modern airliner, fighter aircraft or light propeller (general aviation) plane. Sometimes, though, the realism is all too much, and you would rather just relax and enjoy the views out the cockpit window. For those times, FSX provides a number of options and cheats, mostly accessible under the "Realism" settings tab, that let you turn down the hardcore simulation experience and turn up the fun.
FSX provides sliders to adjust the degree at which aerodynamic forces common to propeller-driven aircraft actually take place in the game. The spinning of a real aircraft's propeller, for example, produces a torquing effect that attempts to spin the aircraft in the opposite direction at the same time; a spinning propeller also generates thrust that is slightly off from the propeller's axis. Turning "P-factor" and "torque" down will produce a smoother ride, making level flight easier and also lessening what you have to compensate for on take-off and landing.
Real aircraft do not spend much time at their maximum speed because of the higher fuel consumption --- airliners, especially, fly the most efficient way possible, even if it is not the fastest way, to save on the cost of fuel. If you find your tanks running empty in mid-flight, click "Fuel and Payload" under the "Aircraft" menu, and then choose "Change Fuel"; you can type "100%" in the text boxes to completely restock your supply. If you do not want to have to worry about fuel at all, choose "Realism Settings" under the "Aircraft" menu, and then check "unlimited fuel." That way, your plane will keep flying happily even with an empty tank.
Flight Simulator X, as of the Acceleration expansion pack, models fighter jets as well as airliners, and the temptation to perform high-intensity manoeuvres can be pretty great. Unfortunately, physics in the real world imposes limits on what the metal and other materials in an aeroplane will withstand --- try to pull too many "G's," or multiples of the force of gravity, and the airframe will simply come apart. You can click "Ignore crashes and damage" in the "Realism Settings" window, and FSX will let you perform any manoeuvres you wish without damage, including rough landings that would ordinarily destroy your aircraft.
If you have missed your landing or feel like it is taking too long to reach your destination, Flight Simulator X also includes a built-in "slew mode" that pauses the game and lets you reposition your aircraft at will. Press "Y" when in flight to enter the mode; the joystick moves your aircraft around on a flat plane, F3 increases your altitude, and F1 decreases it. When you have moved your aircraft to your satisfaction --- adjusting your final approach or giving yourself enough altitude to clear an impending obstacle --- just press "Y" again to exit slew mode and resume normal flight.