I had the chance to visit last year, It was an awesome trip. I visited HackerDojo, YC (Sneaked my way in a party.. but shh :p), Sendhub and randomly attended a trivia-party full of apple/google/linkedin employes, fun time. I wish you have as much fun as I did. Make sure to take coffees a little bit everywhere and pay attention to the conversations around you.. most of the time you'll hear business pitches which is fairly normal in this area.
It's all about the people you meet. Be cool, tell them you're looking to have fun and would love to visit startups and [xyz]. Feel free to email them before you're going there. There's a spot, I don't remember where exactly, where there are literally hundreds of startups. I'm sure there are lots of parties and cool hackaton or events to attend.
