It's a good list Trevor.
I'll add - having a equipment that matches your taste (warm, flat, natural, etc). And I'll second what Hambrabi mentioned, having a good source is important.
But I'll quibble on a couple of the items on the list. I don't think I'd include the AT screen, as while it enhances the experience, it doesn't enhance the sound. Unless what you're getting at is using a vertical center with a projector for a home theater system; then I agree.
And really going out on a limb, I don't think multiple subs is as important as the others; at least for a system used for music. (I'll be hearing from Mojo, I'm sure.) | 
