"do you generally stay towards the small end of the specifications for the sub, the middle, or the high end?..."
I'm not entirely sure what is being specified...I'm guessing you mean how much power we use? I try to match the RMS though sometimes it's a bit overpowered...
I like to make my own box alignment. If thats what you re reffering to...
I like to make mine in the middle because if you make the box small; then the frequency cutoff is too high. I like to get some low bass out of it.
I stay away from extreme low-bass-boxes (labyrinths, transmission lines, isobaric, bandpass, double chamber, abc, etc...) because they make the woofer respond too slow, and reduce efficiency.
I stay away from extreme port lengths too. Ports should be used to fine tune a box, not to provide additional space or response.