I was going to suggest the North Country Trail through the entire U.P. It's about 450 miles or so and almost entirely trail (not much road walking) and it wouldn't be too far from home. Then I saw your comment about wanting to meet thousands of people and that would pretty much throw this trip out except for the sections through Pictured Rocks National Lakeshore (50 miles or so) and the Porcupine Mountains Wilderness State Park (30 miles or so) which are pretty popular and you'd run into a lot of folks.

If it's people you're after the AT is always a good option. Also the American Discovery Trail from Ohio to the Delaware coast would be a good option as it goes through some populated areas including the C&O canal towpath and such.