I just returned two days ago from visiting wine regions in Switzerland (Valais) and Germany (Kaiserstuhl). It depends on how serious of a wine connoisseur your wife is. I usually spend a minimum of 1.5-2 hours at a winery asking a lot to questions, making notes and comparing the wines. I evaluate both reds and whites. We brought back 2 cases of Swiss reds and whites this time. I’ll be going back in November to get the German wines while visiting friends.

I think your task would have been easier if you were in Frankfurt rather than Munich, given the limited amount of time. The FT German residents can give you a better idea of wineries within 2 hours of Munich because I’m not aware of any.

My advice would be to do your homework before leaving on your trip. Depending on the winery, you could be tasting Grauburgunder, Weissburgunder, Chardonnay, Riesling, Sylvaner, etc. Choose a locale, research the wineries in the area and pick 2 or 3 to visit. If you leave everything to chance, you’ll probably be disappointed. The Falstaff wine guide can be helpful as a resource.

An alternative is to find a good wine shop in Munich.