After decades of San Diego Comic-Cons the city may have become accustomed to costumes and heavy traffic for the week in which it resides. However, San Diego will also be playing host to Westercon 68, which is the western region Sci-Fi & Fantasy Convention the weekend BEFORE, over July 4th weekend to be exact. http://westercon68.org/.
And if you are a true fan, costumer, or avid volunteer, you can just stay in San Diego for two weeks, because SD CC will be not even half a week after the Westercon. http://www.comic-con.org/cci
The videos preparing con goers are already up on YouTube, from advice on how to collect the most SWAG while you are there, https://www.youtube.com/watch?v=4YM38wNNv5w
To the must find for The Power Rangers actors and panels.