I've been watching a lot of different stuff, and I'm learning about video and sound as I go. The room is large, and my speakers were able to produce balanced sound in the range from upper bass and above, but the room sucked up all the lower bass. I added a Sunfire sub, and it totally solved the problem. I wired the sub so it was mated with the two mains instead of through the 5:1 sub output. This way, the system sounds as good with two channel stereo as it does with surround.
I'm discovering that the implementation of low bass in 5:1 mixes is all over the map. Some films have absurd amounts of rumbling low frequency pink noise. Ugly sounding. Thankfully, this is mostly crappy modern movies, so I don't have to deal with it often. Rear channel balances are incredibly inconsistent too. Some have just slight beds of ambience filling in. Others have loud stuff going on behind for no reason. On Roy Orbison B&W Night, the vocals came from the front speakers, while Roy's guitar came from the rear. No reason for weird mixes like that.
The difference between bluray and DVD quality is also different than I expected. Modern material, like Planet Earth look a million times better on bluray, but for old movies, there isn't a lot of difference. DVD seems perfectly capable of reproducing color as well as bluray.