Munich in 10 hours

MUC to Munich takes about an hour each way with the S-bahn, particularly figuring time to find the station. Assuming you need an hour or two back at the airport for security, etc, that still leaves you with six hours. I'd start any tour of Munich with Marienplatz. From the S-Bahn station at the airport, there are two S-Bahn routes from the airport. I think either train (S1, track 1, or S8, track 2) will get you to Marienplatz soonest. Just take the first train that leaves. Buy a Partner Gesamtnetz Tageskarte for €20 from the automat. That will cover travel RT from the airport to Marienplatz and any other form of transit you want to use in Munich while you are there. In Marienplatz, you can people watch in the pedestrian zone, visit Frauenkirche (the church with the rounded green domes), or have a meal at the Hofbräuhaus, but you probably don't have time to see the Deutsches Museum or tour the Residenz. If you know what you are doing and watch the time, you might be able to tour Dachau.

I would train to the Marienplatz as Lee suggested. As much as I buy and use Rick Steves' books, I really suggest using the Frommer's Walking tour #1 for Munich. It begins at Frauenkirche, but you could easily backtrack a block and begin at Michaelskirche. The tour takes you past the Viktualienmarkt, Hofbrauhaus, Theatinerkirche (my favorite church) and the Hofgarten. The walking tour ends at the Konigsplatz. From there you jump on the subway south 2 stops to the Hauptbahnhof where you pick up tram #17. Take the tram to Nymphenburg. You don't have enough time to wander much there, but it is easy walking distance to the Hirschgarten, the largest beer garden in Munich. Have a beer and some food, then take the tram back to the Hauptbahnhof. If you have a few more minutes and would like another beer garden experience, the Augustiner Keller is on the way back. From the Hauptbahnhof, catch the train back to the airport.

I wouldn't try to do Dachau on that timeframe. At all. It's S-Bahn to bus and plus the time there....nah. Stick to the Marienplatz area, you will have time to see that/have lunch.

Depending on the day of the week and the time that you arrive at MUC, I would not discourage you from going to Dachau, if that's what you really want to do. The Memorial is not open on Mondays. English guided tours are at 11:00 AM and at 1:00 PM and take about 2½ hrs. Alternatively, you can rent an audio guide and do it at your own pace, maybe faster. There is also an optional 22 min film in English at 10:00 am, 11:30 am, 12:30 pm, 2:00 pm, 3:00 pm which you could watch before or after the tour. However, in my opinion, there are more interesting things to see in Munich. As long as you didn't sleep through high school history class, it's kind of repetitious. It wasn't until my 7th trip to Munich that I bothered to see it. If you arrive on time at MUC and it's during the right time of day, you should have about 4½-5 hours at the Memorial. Figure half an hour to get off the plane, go through immigration, if required, find the S-Bahn station, buy your ticket, and get on the train. Transit in Munich runs on a 20 min cycle. If you take the S1 to Laim, you'll have 9 min to change platforms and catch the S2 coming out of downtown Munich. It takes 10 min to Dachau station where the buses are waiting in front. The bus stop is well marked - hard to miss. Another 7 minutes, and you are at the memorial. Total time from MUC to the Memorial is about 1hr20min, so maybe 2 hrs from arrival at MUC to the Memorial. That gives you 6 hours for the tour and getting back to the airport (1hr20min) with 2 hrs to spare. Of course, it all depends on if your arrival is on time.

I don't think it's a matter of "not being interesting" because a concentration camp isn't really a "tourist attraction" like the glockenspiel, and there is a difference between learning history and experiencing it. Many people find visits to concentration camps to be incredibly important and moving, as a way to contextualize a horror so momentous that simply reading about it doesn't really do it justice. That said, my memories of getting to Dachau (from a hotel near the Hbf) were that it was pretty time consuming, and not something I would recommend for someone with such limited time because it would be the only thing he'd really have time to do without rushing like mad. But now I remember that it was also a holiday when we went and so the transit was running on a slower schedule. That may have impacted my perception of how long it takes to get there. I certainly think it's a must see for a longer (2 days or more) trip to Munich, and some people who have a more active interest or a personal connection to that period of history might find it absolutely a priority over say, going to the Hofbrauhaus.