This itinerary is designed as a brewery tour, focused mainly on Munich, but with a short 2-day loop to the south as well. It assumes you fly into and out of Munich and rent a car there. In the summer, Hefeweizen is the beer to get, although Helles, Pilsner, and Dunkel are always appropriate too.
Take a ride share such as Uber or Lyft to the Weihenstephaner Brewery, spend 2.25 hrs touring and eating/drinking. This is one of the oldest continuously-operating breweries in the world, founded in 1054! When you're done, take Uber again to the Altstadt (historic center) of Munich. I recommend staying in the Hotel Mercure. Take a nap to help stave off the jetlag, then relax for the evening.
This day spent walking around the Munich Altstadt takes you to three churches (Asamkirche, St. Michael's, and Frauenkirche) as well as three breweries (Paulaner, Augustiner, and Spaten-Franziskaner).
This less beer-centric day takes you to the Kunsthalle, two more churches, the Bavarian Museum, and the open-air Victuals Market, where you could eat there or perhaps get some charcuterie to take back to your hotel room. The day does include the Hofbrauhaus brewery.
Rent a car (I chose Sixt for its convenient location) and leave Munich by 10 am. Drive to Ayinger Braustuberl. I recommend eating a good meal here due to the lack of convenient restaurants near your hotel tonight. From there, drive to the Klosterbenediktbeuern. This abbey is where the source songs for Carl Orff's famous "Carmina Burana" were found. When you're done there, drive to the Walchensee on the edge of the Alps and rent a vacation home at the Ferienwohnungen Seewinkel. Take a leisurely stroll around the lake in the evening.
Leave your apartment by 11 am and head to the winter resort town of Garmisch-Partenkirchen, then to the adorable village of Oberammergau. Spend a couple of hours exploring each; make sure to see the painted "Little Red Riding Hood" and "Hansel and Gretel" houses in Oberammergau. Then head to Kloster Andechs for one last brewery tour. Then return to the Munich airport and turn your car in; stay at the Novotel at the airport before flying out the next morning.
Enjoy your trip!