the better bag..?

I think all backpacking bags are lined with synthetic materials this day and age. Silk is too fragile to withstand years of use. Silk can also feel sticky after a few days of use, once it has absorbed body oils and moisture. Wool also retains moisture, takes longer to dry, and is probably too warm for summer use.

The better synthetics — like those used in Western Mountaineering, MontBell, and other bags — really do feel silky soft — and they provide superior wicking and drying properties. They are also very light weight, yet strong and tightly woven to prevent down/feather escape.

Some people line their bags with a coolmax or silk liner to help keep the bag clean. I don't care for the "bag inside a bag" feel. I prefer wearing long silk underwear and a thin pair of liner socks. YMMV.

I think some slumberjack bags have a wool lining. I didn't like my Slumberjack bag much, way too optimistic temp rating, but you may find something you like there.

I've enjoyed my pertex quantum bag. It is very soft, has good wicking properties, and is highly breathable. You want to look into one made out of it if you can't find any natural fibers.

Smartwool microweight long johns and a light quilt work for me over a wide temperature range. The smartwool is pure luxury against my skin. A couple of washings eliminates the minor itching I've noticed when new. YMMV
Tom

Another vote for Pertex, which is used in my Snugpak bags. But these days I wear a transparently thin silk layer in summer time, and wool-1 or capilene-1 layer in the other three seasons. It keeps my bags clean, and I can sliiiide right in.

But, I still remember the look and feel of my families old cotton Coleman bags, and the slightly musty smell of old goose feathers. Pertex and polyester aren't as nice in some way..