Do you mean That Yarn Store in Dublin, CA? Or is there one nearer to you?
As far as Castro Valley goes, I absolutely love Adela's Yarns
. That one is in the CV shopping center. This is where I get my yummy Schaefer anne (I love this yarn)
A couple people in my group go to Color me quilts and they love it for yarn. I have never been, but I think is it somewhere on Nile blvd in fremont.
I have been wanting to visit the many lovely shops out in San Francisco. That is on my wishlist as soon as I can get a chance and my wallet will allow it lol.
I know there are many more around here, just can't think of them at the moment.