I own and drive a GT 3.2 with 18" wheels, have driven a GTA wagon, 156 wagon, porsche 924, hyundai santa fe, nissan sylphy, nissan 350z, vw passat.
let me say that the GTA wagon and the GT 3.2 have quite awful turning radius compared with the rest.
just to give a practical illustration:
The passat, Nissans, porsche have no problems making a clean U-turn onto a 2 lane road.
THe santa fe will need abit more than 2 lanes, maybe squeeze back onto the 2 lane without having to do a reverse if you take a slightly wider entrance into the u-turn.
The GT and GTA wagon has not got a chance in the world. They both take the entire 3 full wide lanes to make a u-turn.
Having said that, parking is not a problem, whether reversing into a vertical lot, or parallel parking along the street. this is because the angles required are not so tight.
hope that gives a better visual picture.
all in all, i think the pleasure of the drive, far outweighs these minor issues.