Gave Warren Dunes a try a few years back. The dunes themselves were cool. If you go, definitely hike up to the top. One setback was that you can't bring alcohol into the park. I wasn't planning on getting tanked or anything, but it would've been nice to drink a beer around the fire. And if you think the rangers don't enforce that rule, you're wrong. Our neighbors got busted for it when we were there. I can understand if you're causing a nuisance, but 2 to 3.... to 4 responsible beers isn't gonna hurt anybody. I'd recommend Nordhouse Dunes in the Manistee National Forest over Warren Dunes.