Be careful with the cross-drilled and/or slotted rotors. In many cases they can actually reduce brake performance.
The point of cross-drilling/venting is to realease the gasses that can build up under the pad during hard braking and to reduce heat build-up. The problem with that is that by drilling/venting you are removing swept area off the rotor, in some cases as much as 10+%. The bennifit that you would recieve from the gas release and cooling would be outweighed by the loss of performance from lack of swept area unless you are constantly running at the high end of your brakes performace envelope. Unless you tow heavy loads daily or are going to an oversized rotor (think 15-20% greater swept area) you are better off staying with a simple factory styled rotor.
A simple and relativley inexpensive way to drasticaly improve your stock brakes performance for towing and oversized tires is to do three things.
1. Change out your pads for a super premium/performance pad (Hawk, EBC, Etc.)
2. Change out your rubber brake lines for braided stainless. This reduces swell in hot and old lines under pressure (and they are also much more durable off-road!).
3. If your breaking system will support it, switch to a higher rated brake fluid (DOT 5). This has a higher silicon amount and a much higher boiling point. If you do this though be sure to thoroughly evacuate all old fluid before filling with the new fluid.
These three things can be accomplished in most cases for much less than $200 and can make a very dramatic improvment in your brake system performance as well as longevity.