I have had two ZT's both facelift. the first was standard specification and had softer springs that the ZT pre-facelift which was apparently critised for a harsh ride. My second and current is a SE model which was 'uprated' with harder sports springs, so same springs as the original. Its the one thing I dont like about the car as its uncomfortable on anything other than a well surfaced motorway, and we dont have many of them! I dont think the big 18" wheels help either.
If I was buying again I would have a Rover 75 or a ZT facelift, but with the 'standard' springs, smaller wheels - and also avoid any car with a sunroof which has been an absolute pain from day one.