Gayfeathers has fantastic fabric, but definitely pricey. It's certainly worth it if you are a serious designer/constructionist, but if you just want to try your hand at something new, it's a little much to spend. Can't beat their more exotic silks and velvets though, ooh la la. I have some hand-embroidered Chinese brocade from there that I'm almost afraid to cut, it's so pretty.
As far as chain stores go I prefer Hancock's, and I've always had good luck at the one on Odana - but that's way across town for me. Mostly I shop at JoAnn's out of convenience and necessity, but if I need anything particular it's better to just order online. For example I have noticed that none of the Madison fabric stores have very good heavier stretch knits or print velvets/velour, but then again it's hard to find those even online these days.