Petoskey is a great place to vacation. The lake is beautiful there. Be sure to find one of the beaches. And while you are on the beach, search out "Petoskey stones" (petrified ancient coral). Downtown Petoskey is a mix of "art" stores, clothing, unique places (like a winery tasting room), and some real good places to eat. Take a drive on the shoreline road to Harbor Springs. Visit the Victorian "summer cottages" that money from Chicago & Detroit built last century. Some are awesome. And be sure to catch a sunset on a beach.
Oh - since you are going to the bridge, eat fudge in Mackinaw City