Just got back from 3 days of bliss. These trails are located near the Mackinac Bridge and have a lot of varied terrain to keep your rides interesting.
Black Lake is 50" inch trail with some mixed traffic areas; heavily wooded with the Boy Scout plantings circa 1911; so you get a lot of trees that are gigantic, but evenly spaced like a corn field. Lots of minor hills with the exception of one large hill near the top of the loop.
Bummers Roost is beginning to show its age. It is extremely sandy and wooped out like mad. About 60% of this trail is Bike only, so your ATV buddies will most likely need to come up with creative solutions to keep up with you. They have had several wash outs recently, so it is rather rocky and stump strewn, so you need to be a little careful your first time through it. In fact, they had to close about 5 miles of it until they can come up with a solution to the errosion issues. This trail has many more hills, with quite a few challanging ones.
They also have a campground that is directly on the trail system called The Bluffs; they have a bar as well as full bathroom facilities that could use a little updating, if you get my drift. There are also 2 state campgrounds within 10 miles of the trails. One is almost next door to the Bluffs, but is a basic campground. The other one does have basic facilities with a communal shower...