Belgian Brewery Tour - advice needed

This year I was finally smart enough to overlap a few days of a business trip with Oktoberfest in Munich. I own a business in Germany and am somewhat fluent, but in over a decade of going over there had never made it to the "Wiesn". For those that haven't been, it was fantastic and I highly recommend it.

Anyway, next year I will be making another trip to Oktoberfest with some friends and we want to extend our trip by visiting some of the breweries in Belgium.

Has anyone done or researched this? Any tips, suggestions? I'm not even sure where to begin in planning this!

Make a trip to the Westvleteren Brewery. I think all of them(Trappist Breweries) would be great to see and try their beers but this one only sells their beer at the abbey. You can get every other Trappist beer in the states.

+1 to Westvleteren