Getting to Muir Woods
 

I am staying in San Fran for two days and one of the activities I'd like to do is go to Muir Woods and Sausalito. Do I need a car? What are my options? How far are they from the city? How far are they from each other?

Heather, you don't need a car to go to Sausalito. On the contrary I'd recommend to take ferry for at least 1-way. Also Golden Gate transit bus can take you from SF to Sausalito over the bridge, so you can take a bus in and a ferry out for different views.

There is a bus going to Muir Woods, the one which goes to Stinson Beach, but I don't know where it stops, and if it's good for hiking.

One of the options is a tour bus to Muir Woods, it takes you to Sausalito as well, and you can take ferry back.

Heather 12,
For Sausalito, no - you don't need a car. The best way to Sausalito, esp. for a visitor, is a ferry from the Ferry Building at the foot of Market Street.
There are van and bus tours to Muir Woods - if they suit your schedule, it would be o.k. to go with one of these - make sure you go EARLY in the day, as the most accessible part of Muir Woods gets a little congested the later it gets. Myself, I'd prefer to rent a car, visit Muir Woods in the morning, and then proceed up the coast another 45 minutes or so to Point Reyes, perhaps stopping at Stinson Beach on the way.
The distance between Muir Woods and Sausalito is about a 30 minute drive.

We had a car and did both in one day. Muir Woods in the morning and then a late lunch in Sausalito. They are not far from one another. I don't know how you would get to Muir Woods without a car although I'm sure someone else will, but, without a car, you can take the ferry from SF dock 40 to Sausalito.

CD, sorry, but it can't be pier 40. All even numbered piers are located on another side from Embarcadero, and the odd ones are in touristy areas. It should be either 41 or 43.

Sorry FainaAgain! You're right. It's probably Pier 41 Fisherman's Wharf. I know we passed it many times on our way to Pier 39 and actually took it to Alcatraz.

You would need powered transportation to Muir woods as all of the above have mentioned but one of the best days I've had in the S.F. area was renting a bike in the city, riding thru the Presidio, over the Golden Gate, and into Sausalito. There were some challenging uphills but also some rewarding downhills. We actually continued on to Tiburon after lunch in Sausalito and then took a ferry with our bikes back to S.F. There were hundreds of bikes on the ferry but it all was very organized. It was a great day.