Use the S-Bahn, the U-Bahn and the tram by 68_snow_man
Munich's public transports are just great. The website bellow allow you to plan your trip. Concerning tickets, there are the one day and 3 days tickets valid for all the inner rings (1-4), which cover most of the town.
To travel around Munich, use the Bayern Ticket. It's a one day ticket valid for five people (yes, 5!) and only costs around 28 euros. It's valid for all Bayern and all public transports can be used (there is one limitation: for trains it's valid mostly for regional ones).
For ticket details, see the links PRICES and TICKETS in the website below. For the Bayern ticket see:
http://www.bahn.de/international/view/en/prices/germany/laender_tickets.shtml
(choose Bavaria)