Hmm, I'm gonna be the only guy here to say I prefer a spring/shock combo over a coilover system for the street.
Most people I know with coilovers on street-driven cars hardly ever adjust the ride height. Most of them complain of knocking noises and rust issues also. The true advantage to coil-overs is the ability to corner-balance the car, for the track. Aside from height/corner-balance adjustments, a regular spring shock combo does the same thing. Most performance shocks offer adjustments for compression and rebound.