There is certainly lots to do in Munich and the surrounding area. You shouldn't have any trouble filling 5 days - it will be harder to whittle things down to 5 days. Some ideas:

• Residenz in Munich
• Augustiner Beer Garden in Munich
• Andechs Monastery - south of Munich
• Regensburg which you mentioned is a nice town to visit
• Ettal Monastery - about an hour south of Munich. Check out the cheese shop since you have a fondness for dairy
• Schloss Linderhof - near Ettal. One of King Ludwig's projects
• Garmisch-Partenkirchen - can spend days in and around that area itself. Lots of hiking opportunities in the area - particularly recommend the Partnachklamm
• Mittenwald - near Garmisch, quaint little town for a 1/2 day visit