Would like to visit a few including the Warsteiner brewery in the Arnsberger Forestpark outside of Warstein. Any input?
They're all good. Some are just better than others. Bavaria is definitely the home of great beers. Rick likes Andechs, south of Munich. I was there, and the beer was very good, but they charged for the tour. :(
Weihenstefan, in Freising, near the Munich airport, is supposedly the oldest brewery in the world.
Years ago I was in Alpirsbach, in Baden-Württemberg, in the northern Black Forest. The Klosterbräu brewery is there and I was advised to take the tour. I didn't, but I have since noticed that the beer seems to be popular all over that area.
With over 1300 breweries in Germany, about half of them in Bavaria, this is a pretty tough question to which you could get more than a few different answers...
On this website you can click on the map and get a list of the breweries in the region you are travelling to. Most of them have their own website so you might find more info about tours.
You can also try this site.
http://www.xs4all.nl/~patto1ro/munibrew.htm#around
I ran into a bunch of Bavarians last week and most of them said Augustiner was their favorite beer and the favorite of most Mucheners.