I was thinking 10.5 or 10.25 or whatever it is. I was really kicking around the idea of a 7" but everyone on barfcom seems to think its too short to be worth messing with unless you just want to make a bunch of noise. Of course, in a SHTF scenario where the ATF no longer matters, the upper can find its way onto a rifle lower and suddenly I have an M4, so maybe a 14" isn't such a bad idea, although I would like for it to be moderately concealable for possibly trunk duty.
I haven't weighed my AR, but its pretty low. I'd like to replace the standard handguard with a Magpul and stick a small rail on it for a flashlight, and I'm not planning on adding anything else. It will be my home defense gun too, if I ever get any ammo. Got too many priorities right now that aren't guns, sadly.