garage attic: one mans ceiling == another man's floor?

Well, ok......it's not anyone's floor but mine. As a refresher, I'm doing a room within a room. I'd like to use the attic floor as the top leaf of my garage practice room. As you can see in the picture it--naturally-- lays on top of the joists. Would it be advisable to lay drywall on top of the joists and then put plywood on top of that? I do store some things up there. I was then thinking about using pink insulation to line the voids between the joists. Tell me if I'm off base here. Thanks.

"Would it be advisable to lay drywall on top of the joists and then put plywood on top of that?" For me: I would install the plywood first. Reason being that there is always the risk of punching holes in sheetrock by climbing around on top of it[sheetrock] when it is overhead and horizontal. But: You want to use it as storage, then if you can be safe enough you could install the plywood last. Depending on the cost of these materials in your area, you may could lay down OSB plywood, sheetrock and then OSB [1/2" OSB being as cost effective as sheetrock with some loss of mass].

Thanks for the reply, xspace. Always a pleasure. Now I'm wondering about something..... If I'm doing a room within a room and, currently, am working on the first room (or outermost leaf of the first room), would it be a better idea--isolation wise-- to attach drywall to the bottom of the ceiling joists? As opposed to putting 2 layers of drywall on top of the joists with some sort of plywood(??) over them? And here's my rationale (flawed as it may be): Wouldn't the exposed joists be a recipe for flanking problems? Since the sound hits them "in the raw"? Or does that really matter if the rooms are totally decoupled? One huge drawback to putting the drywall on the bottom of the joists (as opposed to laying it flat, on top) is the fact that I couldn't really use the space up there as "floor" space, per se, and that's kinda huge. Also, how do people deal with beams that might be a coupling factor between rooms (I'm talking vertical beams)? Any proven methods? Thanks.

The head room from installing the sheetrock on the top side of the joists would be similar in design to the inside out wall that this forum is noted for. A soft ceiling is suggested more often then not so this would again be a move in the right direction. In a room in a room type frame, the interior framing [exposed or not] if it flanks from interior vibration, it flanks no matter which side the panel is on. (I am thinking this is how it is...?) The vibration will go to the path of least resistance and that could mean to by-pass the panel/sheetrock and go to the framing of your interior room. Which is why it is so important to have framing members completely decoupled, interior from the exterior.