If you like to run, you'll love running in the Englischer Gartens park along the Isar River.  Amazing trail system through a spectactular city forest - akin to Central Park, but more heavily wooded.

Most obvious tourist thing is to go to the Marienplatz - you could get lost for hours wandering through there.

Next, and surprisingly cool, is the science and technology museum over by the European patent office.  Very cool city area, and the museum was really fun to walk through.  It had a section heavily dedicated to Einstein, and that was neat to see.

Have fun.

FWIW, there is nothing to see at the Oktoberfest pavilion area until, well, September/October.