The Frankenmuth Brewery has been in operation since 1862 and is the oldest brewery in Michigan. The bartenders are knowledgeable about the various beers and the ambience is very nice. Output is about 8,000 barrels of beer every year and visitors can take a free 20-minute tour of the adjoining brewhouse. Regular selections range from an American Blonde Ale to a Munich Style Dunkel Lager. They also produce eight seasonal beers that are rotated in throughout the year. Tasting flights are very generous. The brewery also has an active restaurant, serving delicious fare. Currently the beer is only available in Michigan. They also produce a robust Root Bier for the designated driver.
If you go:
Frakenmuth is an authentic Bavarian town, since many of the earliest settlers hailed from Germany. In the summer months, the streets are decorated with extra-large hanging baskets of flowers and the gardens along the main street are lovely. There are several stores selling treats and interesting tourist gifts. The architecture of the buildings also draws from the Germanic culture. Zehnder's is very popular for chicken dishes and there is a very large Christmas store in town.
Links:

425 S Main Street
Frakenmuth, Michigan 48734 USA