What's a good recommendation of a Munich 'hop on hop off ' bus tour? I've seen Grayline and the red buses but some of the reviews are really bad.
Unless you have some mobility difficulties, don't go on a bus tour. They get crappy reviews for a reason. It is boring riding on a bus hearing only 1 or 2 sentences about a fascinating building or piece of history.
Go on either a walking tour or a bike tour. For the money, you get a far, far better tour. Read the reviews for recommended tours, either from the RS books, or on Trip Advisor, and check their websites.
It's easily done on your own. Like was said earlier, get a good guide book and enjoy the city at your own pace.
You don't need to do a 'hop on hop off' tour in Munich. It's a lovely city for walking and many of the key things you will want to see are very close together in the city centre. Other sights are very easily accessible by public transportation. There are lots of pedestrian zones and people bike everywhere. You'll have no trouble getting around on your own.