Going to the NBA at Oracle Arena was a really fun night out. It certainly helped that the game I went to (Golden State Warriors vs Denver Nuggets 29th Nov 2012) saw both teams play some great ball at times and also saw the home team GSW come from 16 points behind in the third quarter to win the game. However, even if this hadn't been the case it still would have been a great experience.
From San Francisco the BART will take you pretty much right to Oracle Arena. This is good as Oakland doesn't have the greatest of reputations as an area, and so you might not want to walk about town after dark too much.
You will need to get off the BART at Oakland Airport/Coliseum and from the city centre you can take the line to Fremont or Dublin/Pleasanton. Both of these lines stop at the station.
Then it's just a short walk over a footbridge and around the football stadium to the entrance to Oracle. Once inside you should pop into the GSW team store and look at what's available, and maybe even treat yourself to some merchandise. They usually have an item of the game that is sold at a discounted price for that night, so you might even bag yourself a bargain.
Then go and find your seat to see what sort of view you're going to have. After you know where you're sitting you can go and get some food (if you dare, and if you aren't too afraid of the prices). A beer will set you back at least $10 and the nachos – or corn chips and cheese sauce aren't that great. The cheese sauce has never come into contact with anything resembling actual cheese I'm pretty sure. They'll set you back around $6.25.
Then sit back and enjoy the game. They had the national anthem at the game I went to but I don't think this is the norm. There are also cheerleaders to entertain during the breaks in the game and fun music plays. You might even get up on the big (crazy high def) screen dancing if you're lucky or unlucky depending on if you have the moves or not. There's also the pizza dash where they give away pizzas which I found hilarious. In other game breaks there were acrobatic trampoline dunks and give-aways.
I think that basketball is probably a good sport to go see for people that aren't really into sports because it is such an entertaining game day experience with a lot going on other than just the game. You can also get reasonably priced tickets if you pick the right games and keep your eyes peeled for deals.