Ahh, venturing over here to the wild wild west, very game of you
Good lucky getting in and out of the airport, it's chaos with the "boom" at the moment, bit of an overcrowded place.
There's not much you can do in one night. I'd guess you'd go up to Kings Park and take a look down from there, where you can see the city, hills in the distance and the expanse of the swan coastal plane.
To be honest, I'm not sure of anything particularly riviting within the metro area which is a must do with such a short time ... everything I like about the state is from the edge of the metro area to about 6 hours drive radius
Roger.