where to ride in the Big Horns?

Hi guys. I am thinking on coming over for a holiday with a difference. I have met a guy who is helping a friend in the very early stages of providing a guide service/hunting on a ranch in Montana. I would be a test run to see if they have thought of all the little things. Part of the trip will be into Yellowstone, some days riding (on horse back) and a bit of hunting for coyote and other vermin type animals. Maybe later with white tail or other species.
I would like to get on some trails and do some quad riding with my wife while on the trip and wonder if you guys from the area could suggest suitable places to ride along with where I could rent a quad for the day.
Any help would be good, or even better maybe I could meet up with a few of you and tag along for a ride?