I like Suzuka, because here you can find everything ,all the kind of corners fast ,medium,slow, hairpin, hard braking sections, light brake during turn, Acceleration quick change of direction playing with the weight displacement of the car.....
Everything less bumps. For this, i go to trial mountain for example.
If your car work there and on trial mountain, it work everywhere.
You can ,check your gost constantly and compare your settings......
The only bad thing is that you spend 90% of your time on it, stay very poor of credits or points. But when you have all the cars you need after a certain time of gt5, why money....