First of all, temper your expectations.
The whole thing with having nice amps to begin with is to have dynamic range. In one sense, you're looking to kill it, but OTOH, I do think I know what you're asking.
Different channels simply have louder defaulted levels than others.
I would definitely PM "bandphan", because I remember he recently recommended some sort of in-line device that can help out with this on TV signals.
My impression of Dolby Volume, and similar technologies, have to do more with dialogue intelligibility mixed with action effects. Probably related to the whole Fletcher/Munson thing, but to be honest, I'm really not up to date on how these "similar technologies" work. I already forgot the difference between Audyssey Dynamic Volume vs Dynamic EQ, for instance.
Commercials suck, period. My advice is to use the mute button, or record on a DVR and fast forward. Like I said, temper your expectations. The advertisers are paid to compress at a maximum, and if they didn't, they would be out of a job.