A RAW file can contain mountains of information about a shot. The below photo was processed from a single RAW file of a sunset this afternoon. In the original file, the sky was slightly blown out and the ground was very underexposed.
The RAW file contained enough information for me to bring back the sky and also lighten the foreground just enough to not create silly amounts of colour noise. If you want even more dynamic range you may need to blend exposures. The photo below is a composite of 2 RAW files blended in photoshop. One was exposed properly for the sky, and the other for the foreground.
Blending the two exposures using layer masks in photoshop allowed me to capture a much wider dynamic range in the image. The foreground is brighter and more saturated.