In Appleton, you could go to the Fox River Mall food court and see the (Fratellos) Fox River Brewing company's setup (yes it's in the mall) as you walk in it's to your left; or just drive downtown and go the Stone Cellar Pub (Olde Oneida St.), Fratellos or one of the many, many bars downtown (College Ave).
In Green Bay, you could go to the Title Town Brewing company on Dousman street right before the river and sample their brews.
You may want to drive by Briess industries in Chilton (just to see it and say 'ahh that's where it's made!').
In Oshkosh there's a lot of history (Gambrinus Brewing and Chief Oshkosh beers, red lager)...