I'd suggest making the inside with a slippery fabric (think lining, taffeta, etc.).
If you use a cotton, then the garments stick to it, and harder to keep all hanging properly. And harder to work with as you put garments in and out.
Quilting would add more bulk and weight ... and yes, would provide more protection. Back to the lining suggestion, perhaps use a nylon rainproof fabric for both inner and outer fabrics?
From a design vantage, you might want to consider a gusset all the way around to allow for expansion rather than what is hung in there being compressed and thus more likely to wrinkle.
Another suggestion would be to add a separate pocket at the bottom that smaller items could be put in, and not be floating around in the main bag. I have one bag like this, and depending on the situation, sometimes I keep shoes in there. Other times, lingerie, pantyhose, small purse, etc. Sometimes it holds a few toiletries that I might need.