Georgia B's Quilts, W1044 Old Portage Trail, St. Ignace 906-643-7726. There are 2 in Sault Ste. Marie, but that's an hour's drive north. If you can get your hands on The Country Register (Michigan version -free at local quilt shops) it has a very extensive list by city. I keep it in the car and check it for any city we may be traveling through. DH is always happy to stop @ quilt shops for me.

Everyone has given good ideas of what to expect on the island. Rent a (very comfy) bike while you're there. The island is not that big and you can bike around the shore in an afternoon...with plenty of stops. ENJOY!

I have been to Mackinac Island many times. You didn't mention whether you were staying on the island or which side of the bridge you were coming from. There are plenty of places at different price points to stay on the island but would recommend reservations. The same goes for Mackinaw City or St. Ignace. My cousins own a resort, Pines of Paradise, which is just south of the bridge that has nice cabins on a lake. They have a website. If you're not from Michigan or the area here are some tips. If you are then my apology for telling you things you already know.
Here goes:
Even though it is spelled Mackinac the name of the island is pronounced Mack-i-naw (rhymes with paw)
Tourists are called Fudgies - you'll understand when you see all the fudge shops
People who live in the UP of Michigan (upper peninsula of Michigan) are called UPers - pronounced YOUpers because of the many Scandinavian residents who sound their o's as ou's
People who live in the Lower Peninsula according to the UPers are called Trolls - live beneath the bridge.
A staple of northern Michigan, especially the UP are pasties - pronounced PASTees. If you can get some locally try them.
There is a fort on the island that worth the visit from a historical point and the views from there are nice
There are no cars but the island is small so walking is not a problem. You can also take a carriage, rent a bike or a horse. You can take your own bike over on the ferry for a small fee if you want.
If you are not staying on the island don't miss the last ferry back to the mainlaind!

Hope you have a great time. It is a touristy but magical place.

Thank you so much for the information everyone! I'm starting a list. Thankfully my friend and her mom know where my passion lies and are happy to stop at all quilt shops. We'll be driving up (I think it's up, since I'm not from back there!) from Ohio, so there should be ample opportunity to find fabric. I failed to mention that we are actually staying in the Grand Hotel and it is actually called Girlfriend's Getaway. I'm looking forward to not seeing cars for a few days. We're getting together this week for make all the reservations. I told my DH I'd be gone for about a week and a half, because we also want to go to Hershey Pennsylvania!

There is a great quilting shop in Gaylord. Call Ice House. Love to shop there.

If you are driving up I-75 from Ohio, I would recommend stopping at "The Village Quilt Shop" (exit #84 north of Detroit). Delphine's Quilt Shop in Gaylord is a few blocks from the highway (exit 282), and absolutely worth a stop.
Mackinaw Island is a magical place -- enjoy!

Miki in Northern Michigan

I've lived in Michigan my whole life and have been to Mackinac Island lots of times. My DH and I are going a couple of times this summer. Our vacation home is 20 minutes from Mackinac City. There are 2 quilt shops in Midland, several in Saginaw, one in Pinconning which is just a few miles off I-75. When you get north, there is a nice shop in Indian River and a small one in Cheboygan. Have a great time!

Sounds like fun. We are going to be in MI in Aug cant wait. Got three friends Travers city Saginaw and a little place called Chase we are going to visit.

The Ice House Quilt shop is in Greyling not Gaylord. It is a great shop. I live about 25 miles from and have been there many times.

You'll love Mackinac Island; it's truly a magical place! If you're able, be sure to rent a bike and travel all the way around the island. It's an easy trek, and you really get to see things including nice spots to rest and wiggle your toes in the clear blue waters of Lake Michigan. Since you're staying at the Grand Hotel (lucky you!) be sure to partake of an Afternoon Tea. And also be sure to walk to the left of the hotel up a short stretch of road -- the homes there are well worth seeing. I don't have to tell you to relax along the veranda in the rockers and take in the view. Enjoy your wonderful trip!

Google your heart out. There are many really nice shops on the way to and form the upper peninsula of Michigan. The Travers City area has several that I have been to. None on the island that I am aware of. I looked when I was there two years ago. But I would not be surprised if Sault St. Marie has quilt shops. That is where you will launch off to the island. I know that there are a couple in the Cadillac area, but it all depends on how you are getting to the Island. PM if you want more specific info.