Went to SF in 2008 and saw two games. If you can swing the cost on StubHub try to get the club seats next to/behind the visitors' dugout. They're great seats and come with access passes to the club below the seating bowl. The great thing is the players use the same area to get to the clubhouse as the fans do to get to the club. From that area you can also go watch the players taking BP in the cages during the game. After the game we met a couple players and were able to talk to them for a few minutes before they headed back to the hotel.
I would stay in SF opposed to Oakland. My wife and I have traveled every year to see the Tigers on the road and I used to go see the Lions on the road every year and SF is hands down my favorite city. It's so different than any other because of the natural uniqueness. Plus the public transportation is outstanding with the cable cars, street cars and subway. If you do stay there, try to ride the cable cars after 10pm. The city at night is great and there won't be as many people on it as during the day. We rode it around 10:30pm and were the only two riding. The driver was showing us how to drive it.