We spent 2 days at Silver lake sand dunes and 5 days in the Grayling/Gaylord area. In that area there's hundreds of miles of ORV trails, logging roads and oilwell roads covering about 400 square miles. GPS and trail maps are a must, along with a cell that will get reception in that area. It's a combination of flat, wooded sandy terrain, steep hills, deep ruts and dense woods. It's generally foolish to go out there alone, but I know the area well enough. We still had some "Oh Shit" moments though.
I just bought a 2010 Wrangler Unlimited, it's still stock so we picked everything that was medium difficulty. It's getting lifted this winter and I'm throwing a winch on it. My Grand Cherokee never really sees any action...it's just a grocery getter.
All the sand in these pics is DEEP. For the most part I was aired down to around 12 psi and still getting stuck occasionally.
Our WJ and JK






That's Lake Michigan in the background.....













