I have a 2005 C6 with Z51 and I thought the suspension was comfortable. I have since moved to coilovers and...um...yeah, no longer as comfortable but the handling is SOOOO much better.

Swap out your Z51 shocks for base shocks.

Leave your Z51 sways one though and see how you like it.

I added the Z51 sways on my base car ( poly bushings though ) and really like ride/handling. So I currently have the base shocks with the Z51 sways. I am also runing the Firestone run flats that put up a better ride over stock the OEM tires.

If you do the base shocks you will still have the spring rates of your Z51 that are stiffer over the base springs.

I've heard Bilstien sport shocks will soften the ride, maybe I will try them. Thanx guy's for all your replies.

According to other reports here, and my experience on our C5:
Bilstein HD's are designed to work with the base suspension and will soften the Z51 ride somewhat.

Bilstein Sports are designed to be a Z51 replacement and will ride similar (but not identical) to the original Z51 shocks.

The judgement of how good a suspension system is, how well it keeps all four tires in contact with the ground at all times, for the simple reason if that if the tires aren't in contact with the ground you can't steer, brake or accelerate the car. A by-product of keeping all four tires in contact with the ground at all times is that the car is easier to control and will provide a more comfortable ride than one which doesn't. No suspension system is superior to the F55 Adjustible Magnetic Ride Control suspension in this regard, that is why it is the standard type suspension on virtually every supercar built today. The Z51 suspension is pre-computer, obsolete, inferior technology favored by those that think a sports car should ride like a shopping cart. Old-fashioned technology for old-fashioned thinking.