I've taken four trips with BeerTrips.com, two to Belgium, and will be visiting Spain with him next year. On the Great Beers of Belgium trip we visited Cantillon, 3 Fonteinin, Rochefort (they only allow 4 tours per year, so it's a coup), Orval, De Halve Mann, Rodenbach, Liefmanns, De Cam, Slaghmuylder(Witkap), and De Konick. The itinerary varies a little by year depending on brewery schedules. I know this year (going on right now) they're visiting Du Pont and Chimay. Our second trip was somewhat custom, as it was all repeat travelers. In addition to the above, we saw Rulles, Kerkom, Vapeur, and the Westvleteren cafe.
Beyond the breweries, we visited many iconic bars and restaurants. The walking tours of each of the cities were fantastic.
Having taken four trips and planning a fifth should give you a good idea of what I think of Mike's tours.