I'm considering taking a small building down to studs & siding.

Then, the question would be, what to cover the walls with? Perhaps fiberglass batting insulation, raw side to the room, and a cloth covering?

I don't want to be on the wrong side of flammability, but, I'm hearing terrible things about the chemicals used to fireproof cloth.

Then, assuming this goes forward, there are issues of supporting the batting so it doesn't sag...

The goal here is to create multipurpose space, about 17'x20', to be used as an insert studio (video/audio), and office space.

Ideas, web sites, things that have worked, things that haven't?

Usually a recording studio is built or renovated with 'sound transmission levels' (STL) in mind first. Keeping extraneous noise out / internal noise in, which could mean, double-walls, double-glass, lead sheeting, fiberglass, cement, filled cinder blocks, floating floors, walls, ceilings, ect. An extremely quiet HVAC system is another area that should be considered. Then address the interior acoustical reflection control. Three very different areas of studio construction.
I would suggest searching "Recording studio construction and design" and "Sound Isolation Strategies and Indoor Noise Reduction" for books and information and peruse information and services available from the acoustical treatment manufacturers like Auralex.

Thanks for those suggestions. I'm glad to say that isolation is going to be easy (!), due to the quiet location. I should have mentioned this in the first post.

Since the space needs renovation down to the studs/siding anyways, and is quiet, I have a somewhat unique opportunity to not use drywall as a wall surface, so, I'm wondering about alternatives that will be better for reflection control.

Most interesting so far is FabriTrak (http://www.fabritrak.com/), a channel system by which various fire-rated and acoustic-rated architectural fabrics can be stretched to look like panels. Behind the fabric? Something absorbtive...?

Auralex has a 'free room treatment analysis' that may be useful.
Auralex Acoustics - Product Application Support (http://www.auralex.com/pcf/default.asp)

Home Recording - Powered by vBulletin (http://www.homerecording.com/bbs) has a studio topic where this is discussed ad nauseum.

Most of the soundstages I've seen appear to have what appears to be expandable foam (or something like it) between the studs. Appears to be shot in as a liquid which expands, and then some fine mesh appears to be fastened over it (much finer than chicken wire -- I'd say about 1/4" mesh). When we remodeled our house I remember looking at a home level product called Icynene. Huge insulating and sound-deadening properties but somewhat expensive.

Then you can drape anything you like over it.

I've always been quite happy with hand woven thick wool carpets on the end walls and bookcases full of interesting odd shaped books on the side walls. Looks good, sounds good and has a good natural vibe.

Thanks all, for the great ideas - research continues!