Personally I use MS Flight Sim 2000 Pro with all options to MAX!!! It needs a beefy PC, but if you have the right spec it looks beautiful. When you install it select to install ALL scenery to hard drive. Then when you run it go to the Display Options from the menu within FS2000 and turn everything up.
I especially love the aircraft that come with it and have fully animated moving parts. It's very precise. Flaps, Engine Intake Fans, Landing Gear, Aerilons, even the nose on Concorde!! etc etc... (Although for Concorde, I prefer the Concorde SST add-on!! - it flies better

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You can go to spot view and use the hat on your joystick to move around the aircraft, and when you fly over somewhere like London (that I know very well) it does look pretty damned good.
Brilliant. I love my flight sim

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If you want a more Military style of flying, check out B17 Flying Fortress - it uses Hardware Transform & Lighting (so my GeForce makes the most of this!), and looks great...