I was also thinking Fieldstone house but Zooks in Intercourse PA is also packed with loads of fabric. Some people have said it looks more like a hoarders than a fabric shop. Fieldstone House you have to call in advance (a few days to play it safe!) to see if they are there as they spend most weekends traveling to quilt shows as a vendor.
Edited to add, I would opt for Zooks as that is right in the heart of Amish country and there are loads of shops in the area and all are very reasonably priced.