Are there any special fare cards that are valid for a couple days either on buses, MUNI or the trolleys? And BART, if that's an option.

It is my understanding that there is a special pass that you can purchase that is very reasonable and will give you 3 days on any MUNI system which would include the buses and the trolleys. You could check with the Chamber of Commerce or with the hotel where you are staying.

The MUNI website is magnificent.

We bought one day passes through the MUNI website two years ago. $6 for all day use of cable cars and buses.

You can buy your Muni passes at the airport. But it is not good for BART, which is a separate system. We rode all over SF on our 7-day passes for $15. The buses are easy to use and we loved the cable cars! Have a great time! Don't forget the Cable Car Museum. It's free and very interesting.

We were in recently in San Francisco and purchased a three day muni pass for $10. I think that they are also available in 7 and 10 day passes also. It gives you access to the muni buses, the cable cars and the muni subways (which are different than BART but run some of the same routes). I found them a great value and a great way to get around SF.