I have gotten so comfortable with the 5 frame brackets with the K5 using the +/- 2 ev that with the sensor, it picks up just about all the dynamic range available.
There is another (there is always another) HDR/tone mapping software utility - Oloneo PhotoEngine. It has a free 30 day trial that you may be interested in.
One aspect of this program is the ability to take several sets, each set with different light sources on, and then blend each set together. For instance, you might shoot a 5 frame brackets with just window light, and then another with lamps on, etc. - and then blend them together. They have a video on doing this.
The nice thing about their 30 day demo, is its not crippled at all.