Drilled/sloted rotors used to be a popular topic over at LS1tech.
Drilled rotors were used years ago on racecars because it helped the pads outgas. However, this is no longer an issue because pad technology has advanced a lot over the years. People liked the looks so....
Drilling rotors reduce their weight therefore the amount of heat they can absorb from friction is reduced. They often crack around the holes. Drilled rotors also have less swept surface area, are weaker (because some material has been removed) and are more prone to warping. Drilled rotors do not improve braking in any way.
Some makers have almost eliminated cracking by casting in the holes or chamfering them after drilling-but it's still no improvement in braking.
http://www.bing.com/images/search?q=cracked%20drilled%20rotors&qs=n&form=QBIR&pq=cracked%20drilled%20rotors&sc=1-22&sp=-1&sk=
Slotted or dimpled rotors have less pitfalls then drilling but again, they offer no better braking performance.
Extreme disc brake applications such as aircraft and railway use blank rotors-never drilled or slotted.
I've used expensive two piece Wilwood rotors and cheap blank rotors on my Trans Am. I've found virtually no difference in braking action. I'll always use a name brand blank rotor such as Bendix, Raybestos or Centrix. Anything more expensive is, well, just more expensive. Today, most all are the same rotor from Asia or Canada anyway.
What does help is better pads. I use EBC Yellowstuff race pads. They're amazing. The hotter they get, the better they grip. When doing a long stop from speed, you'd need to start easing up on the brake pedal to maintain the same braking rate. I use them on every application they make them for-including my truck. The current offering of low dust ceramic pads seem to work well for a daily driver.