New Holland's, "Dragon's Milk" Imperial Stout is worth finding and drinking while you're there if you're into Stouts. I like it almost as much as Black Butte by Deschutes, or Pisgah's Brewing's Nitro Stout, or Founder's Imperial Stout.
Without knowing your beer preferences ill just list breweries that I enjoy and that should be available at most decent party stores. Arcadia has a nice line, Shorts Id recommend, Founders, Hometown Cellars has some nice beers but they might be hard to find, Tahquamenom Falls has several good brews, and of course Bells. Oberon is their summer beer and Im sure their highest seller but Two-Hearted is basically the best beer you can get your hands on.
That was it? You made a thread to try 1 beer? If you make it down to Asheville, NC plan to try a few more than 1. Could be Michigan only has 1 beer it can make.