In Northern California Bay area I say Queen B's, Antioch CA. It doesn't look like much from the outside, but it is huge, and the staff/owners are very friendly. They have great sale days: 3rd Tuesday of every month is Quilt Back Tuesday where you bring in a completed quilt top and can purchase the quilt backing at 30% off, also they have a fabric of the day, one bolt (apparently chosen by the first customer of the day, the fabric that is sold the first of the day). Lots of batiks, Kaffe, Aboriginal, and lots of traditional fabrics.
Hope you make it out here. Also, a couple good stores near Queen B's is Wooden Gate Quilts in Danville and The Cotton Patch in Lafayette. These are my favorites in the Bay area, but there are about 20 stores in East and South Bay areas.
http://www.queenbsquiltshop.com