G.E.
Coilovers will offer the best ride, and suspension set up for your camaro. A set up like pfadt racings units
http://www.ipsmotorsports.net/produc...oducts_id=3477 The coilovers valving is better engineered for high performance and higher rate springs. The coilovers also will have adjustable dampening, which will allow you to set the rides stiffness or softness to your specific liking. So a softer setting around 2-4 will ride smoother over the road then say 14-16 . The coilovers will also allow you to adjust the ride height on the car with out sacrificing suspension travel, which is commonly a problem with lowering springs on stock struts. So in the short summary, coilovers are going to offer you maximum performance, but may be a little over kill.
If I was recommending a set up for your camaro, It sounds on the surface that you looking for a more basic setup, to lower the stance of your camaro and also have achieve a smooth ride. The lowering springs will shorten the life of your stock stuts due to them not being designed to have the proper shock valving for the spring rate upgrades that eibach, pfadt, or H&R offer. They will wear the shocks from our experience 20% faster, and you will notice once the shocks wear out when the car has a much bumpier feel and may travel to the bump stops more often. But don't worry this doesn't happen over night, typically takes about 25-40k miles depending on usage. In short on the lowering springs, yes they will shorten the life of your factory shocks, but the shocks will still last a fair amount of time, they will ride similar to stock, but offer a lower center of gravity, and a better feel.
Good luck, if you have questions feel free
Regards
-Brandon