yea bike and quad trails.
Yea, Drummond Island is going to be hard to beat then. You've got both the MI DNR trails & routes, and then the private Turtle Ridge ORV park. (
http://www.turtleridgeorv.com/)
Wa-Wen campground is very close to the trail. They have cabins for rent too.
http://www.wa-wenresort.com/html/wa-wen_resort___rv_camping.html
When you get on the island, stop at the Bear Track Inn. Great breakfasts there and the owner (steve) is big into ATV/ORV riding & can fill you in on all the best places to ride.
Lots of trail info here, including a ride video:
http://www.vvmapping.com/trails/drummondIslandRoute.html
I wouldn't suggest going in the Spring time unless you *really* like to get wet/muddy & have friends with winches. There's mud/water holes there that are 8' deep easily. Late July or after is generally the best time, esp once the black flies die down. Trails are probably the most difficult in MI, but easy compared to anything in WV/TN. Trails are a lot different than the L.P. DNR trails... almost all hard rock trail floor, no sand... lots of water and mud puddles, some climbs, views of Lake Superior, etc. Def air down your tires. Only real downside to Drummond is that you have to take a ferry to the island, and back, and that adds to the drive time. About 7 hours if I recall correctly... but it is an experience.
I've also ridden a lot in Luce county by Rainbow Lodge and the Two Hearted river. DNR trails are nothing to write home about, lots of deep, loose beach sand - certainly wouldn't want to be on a bike, personally here. ATV would be OK. Not even close to Drummond though fun-wise. Bill Nichols trails over the west side is fun for a dual sport bike ride, but would be fairly boring for ATV/dirt bikes.