Warning! DRESS. WARM. It is really cold on the water.
Another warning! You will arrive at the bridge within 10-15 minutes of the cruise starting. DO NOT stand in line to get a drink right once you get on. We almost missed the golden gate bridge because there was one girl making drinks and it took 20 minutes to get to our place in line and there were only about 5-6 people in front of us. So, go to the top and enjoy the golden gate view and take your pictures so you're not rushing. Then, once you turn around and head toward Alcatraz, go get your drinks. Plus, it's so windy on the water, it makes it hard to hold your drink and take pictures.
After the golden gate, it's a chill ride. You just go by alcatraz and the other bridges (which actually look really cool too) that's a good time to sip on your drink and enjoy the view! Nice, relaxed sail.
Also, it's a pretty big boat with an inside area, bar, bathrooms, etc. so don't expect a little speedboat or anything. They also only asked for the last name when we boarded, so don't stress out about having your tickets ready, you likely won't show it to them.