UP will still be chilly, many Great Lakes based attractions, ship wrecks, museums, lighthouses, old school live off the land things to see. Very interesting topography. The Mackinac Bridge is very cool. Heck they still may be skiing at Boyne. I don't believe the golfing around Traverse City will be up and going yet, long winter has created some greens problems, even down here. Grand Rapids is a great town, a jewel in MI. Very clean and just a pleasant place to visit. Toronto is several hours away, the National League Hockey Hall of Fame? A UP link
Things To Do in Michigan - Upper Peninsula Regional Attractions