So here's what I found out: Most dealers DO use standard dyed film, and they charge an arm and a leg for it. The step up from dyed is the metallicized/dyed film, but that can cause problems with your radio reception, cell phone signal, and GPS signal. The step up from that is full metallicized film- but that often causes interference because of its full metal properties. The best film to use (if you don't want the purple fading attributed to dyed film, and excellent UV and heat blocking properties) is ceramic film provided that you have electronics in the car that can be interfered with. Full ceramic film will NOT interfere with the reception of any electronic object.
Additionally, the best shops will have a full line of a manufacturer's product, and not just a few lines. Beware of the ones that only have (for instance) 3 out of 5 lines of SolarGard- the good places carry all of them. Also- the best shops will NOT use more than one piece of tint for your back window. The best tint I have found is Formula One and Huper Optik as far as their ceramic line goes.
And as far as percentage? The lower the number, the darker the tint. However, all tint percentages are not created equal. I used a 15% Formula One Pinnacle tint by Formula One, and because my car is the cashmere color on the inside, but black paint on the outside, the tint does not look nearly as dark as it might otherwise look with a black interior. Try to find a shop that will help you visualize your tint by putting pieces (large ones, if possible) up to the window so you can get a clear picture of the tint's look on your car. Remember, you just spent $50K+ on your car, so don't let them rush you into putting just anything on there.
Oh- and as far as places to go? I called around, asked what kind of tint they used, and asked to see samples. I visited a few places, all of which I found by using the online yellow pages. If you feel like coming down to Orange County, I'll refer you to the place I used- they did an excellent job.