I don't own a C5, but since day one of owning my C4, I have had mud flaps on it. I think they are an invaluable source of protection.
If I was racing the car competitively, obviously, I wouldn't use them, but for street use, I think they are perfect.
The front and rear quarter panels tend to wrap underneath and behind the rear of the tires, therefore they take the brunt of road debris.
Over time I have noticed the most damage occurs on the rocker panels starting in the middle of the door where the surface area of the splash guards cannot protect. Basically, you can't really avoid this.
As far as what type to use - it all depends on what you think looks good. Go to a local Corvette show and take a look at what other C5 owners are using so that you can get an idea of what might look good AND be functional at the same time.
Below, you can see the mud flaps that I'm running on my C4. I chose these because they are not only functional, but from the rear of the car, they tend to blend in with the tires: