Fleet Week... This can be a very fun time of year for visitors and the weather is typically incredible. I used to live in a building that allowed me to watch the Blue Angels (see photo) air show from my front window. You can wander in to bars at this time and meet some really interesting people. One year I ended up on a cable car with the Marine Corps Band and the played songs the whole ride. Definitely a rather interesting night.
For more Fleet Week info, check out http://fleetweek.us/fleetweek