bring back lots of wonderful memoires, they far outvalue anything else
If you can find it (it's been out of print for quite some time), I would recommend
The Last Year of Thomas Mann. A Revealing Memoir by His Daughter, Erika Mann (1958).
Incidentally, Erika and her brother Klaus (author of
Mephisto) fled Germany in 1933 after the Nazi's took power. The two of them had founded a Munich cabaret called Die Pfeffermühle, which specialized in political anti-nazi rhetoric. They left for Zurich and had their German citizenships revoked by the Nazis. Effectively a ship without a port, Ericka, who was a lesbian, took up a marriage of convenience with the English poet W. H. Auden, who was also gay. The marriage bestowed Ericka with British citizenship and she became a prominent journalist and covered the Nuremburg Trials.
Klaus, also gay, ended up as a staff sargeant in the U.S. Army and wrote many reports from postwar-Germany. However, his homosexuality, combined with his radical political views, got the attention of the FBI. He ended up committing suicied by overdosing on sleeping pills in 1948 in Cannes.
I'm sure there are plenty of other great memoirs you can bring back from your trip. The saga of the Mann family, for me, is one of the many great stories of Munich.