big rig campground at sleeping bear dunes, pictured rocks

Thanks for all the info. We have decided since we only have 4 days left to fill we need to chose either Mackinaw Island area or Sleeping Bear Dunes. We have been to both areas but only for a day or less and didn't get to see much (absolutely loved both). We want to hike, bike and see nature. What areas and points of interest would best suit us before heading to Pictured Rocks area? We would like to stay at Platte River but afraid we don't have a chance of getting in there Aug 22-25.