Actually, I did, but at the time it was cost prohibitive, especially since I (reluctantly...!) had to build the rest of the second floor, too. Since you're bare bones at the moment, it might be worth looking into, for a bit more isolation. Check out the acoustics thread(s) and see if anyone had good luck with second floor sound isolation using that. If I remember, there's a couple of versions of it, according to thickness. I think it will help, but also may be more for isolation of footsteps, "thumping", etc. Keep in mind weight considerations, plus thickness for your door jamb clearances, too. Although, if you use exterior grade doors, the threshold will be pretty high to begin with, so that might be a non-issue.