Going to Munich, what should I not miss seeing?

I still have fond memories of this when my wife and I visted Munich

https://en.wikipedia.org/wiki/BMW_Museum

That trip we visited museums in London and Paris and the BMW museum still stuck in my head. It may have changed since then, that was quite a few years ago.

Well rated at tripadvisor as well

http://www.tripadvisor.com/Attraction_Review-g187309-d190264-Reviews-BMW_Museum-Munich_Bavaria.html

Not sure when you are going but if you are going to Munich at the beginning of May, then the High End is the THE place to go in Munich:
http://www.highendsociety.de/english/highend/highend.php

Munich is also full of record stores:
http://muenchen.cylex.de/branchenbuch-muenchen/L1c1-D_O1c1-M%DCNCHEN-P1c1--N1c1-SCHALLPLATTEN.htm

Also, this is the official site for Munich tourism:
http://www.muenchen.de/int/en/

Rick Steves European travel shows on KCET are among the best. He's been everywhere. Here is his site with advice:http://www.ricksteves.com/

All the best,
Nonoise

Take in the Hofbrauhaus for sure.