When I spent my first week at Disneyland, I was HQ there (and went there at least once a day to do something), but you are correct. Especially if you are at all interested in the entertainment industry.
Of course, there is Universal - but WB also has a great studio tour (of the real studio, not a studio/themepark hybird), several awesome museums with content you can't find much elsewhere, Sunset Blvd (the real one! LOL), the Hollywood Walk of Fame, more classic iconic buildings and architecture than you'll find east of Washington DC, heck - you can spend a couple of days just driving around and visiting famous movie locations (Want to see the Nightmare on Elm Street House? LA observatory - from every film from Rebel Without A Cause to Charlie's Angels? You can!).
And that's just the tip of the iceberg.