Country Stitches in East Lansing is a wonderful shop but a bit out of the way. Fields Fabrics is a fabric (not just quilt) store but they have wonderful quilting fabric. That is in Grand Rapids and a few other places. Not at all like the chain fabric stores. I haven't shopped at the one in Grand Rapids as there is also one in Kalamazoo where my children live but I understand the one in Grand Rapids is even larger and the one in Kalamazoo is large. Grand Rapids is their home base.
Fall in Michigan is beautiful and you shouldn't freeze. I grew up in Michigan and go back every year in the Fall. Both of the shops I mentioned above are on my must visit list.