Help with planning a trip to upstate michigan!?

A group of friends and I want to go traverse city, mi or mackinaw island for the weekend. I've been looking at visitors guide and a bunch of other websites but I want information from people with personal experience. We're all college students who enjoy lodging, outdoor recreation, food and stuff like that. Can you recommend vacation packages, things to do, places to stay, activities, and narrow down whats worth doing within the time frame because we only have 3 days. Also, we don't have the biggest budget, so what is there to do for free. Thanks in advanced!