Sunrise,
Start by setting a bookmark at
RV Park Reviews. Next decide where you would like to go, and find the parks there. When you have a park in mind, run them though the above site. When that is done, then go to Google Earth and locate the subject campground and see how well GE fits with what you have learned.
Michigan has lots of campgrounds. Some are beautiful and some are crampgrounds. That is what that site is for. If you know when and where you are going, make reservations during the season. The good places fill up fast. You also will need the 11$ sticker (Michigan Recreational Passport) that you can get with the vehicle registration, The Sec of State or at the first park of the season.
Matt