If you plan to tour San Fran at all you may want to consider travelling as much as possible on foot. I have been there twice and the traffic was a bear both times. Also, if the six of you are going to need to travel by taxi they will make you use two cars due to the size of your party. During rush hour it may be cheaper to hire a stretch limo since they charge a flat rate that you can sometimes negotiate. I was there on business three years ago and the hotel staff tipped us off about that trick. It ended up saving us a bit of cash and the driver was more professional than the cabbies. Finally, be prepared to see LOTS of homeless people and beggars in the city.

On the upside, there are a lot of fine restaurants all over the city. I think they have every cuisine you can think of. They have a good mass transit sytem downtown and the streets are in a grid pattern form the most part so navigation is easy. Also, people are generally very friendly ( as compared to the eastern US at least).

Have fun!

Chris